Friday, September 27, 2013

Cocaine on Currency: The Innocent Contamination Defense and Recent Forensics Research

Additional Note:  This blog was posted in 2013 and in April 2016 seems to have become of some interest again.  It has not been updated since its original posting, but there have been both legal and scientific developments.  These are discussed in three separate chapters in the forthcoming Canine Olfaction Science and Law, i.e., in Chapter 15 by Professor Leslie Shoebotham, in Chapter 17 by Professor Thomas Jourdan, and in Chapter 9 by Professor Megan Ferguson and me. 

An influential 2005 case of the Seventh Circuit, U.S. v. $30,670, 403 F.3d 448 (8th Cir. 2005), determined that a drug dog’s alert to currency could help establish a connection between the currency and illicit drug activity based on the scientific conclusion that the substance that dogs were detecting on the currency was methyl benzoate, a byproduct of cocaine undergoing hydrolysis due to moisture, and that methyl benzoate is only detectible for a short time after the currency contacts cocaine. Thus, innocently contaminated currency should not trigger a dog’s alert unless the innocent holder received the currency shortly after it was in contact with cocaine. Since this was generally a factual issue, a defendant who had held the cash for more than a few days was in trouble. (For a discussion of the history of currency sniffs, see Police and Military Dogs, Chapter 15, 207-214.)

Now the Seventh Circuit has issued a decision, which may not be the last one in a case that has been going on for 11 years, allowing for the possibility that the science that it previously accepted as definitive might actually be undermined by other research. U.S. v. Funds in the amount of $100,120, No. 11-3706 (7th Cir. 2013)

Briefcase at Chicago Train Station

On December 4, 2002, Vincent Fallon purchased a one-way ticket for a train scheduled to travel from Chicago to Seattle on December 6. Drug Enforcement Administration agents see one-way tickets as a possible indication that a passenger is a drug courier. Two agents approached Fallon after he boarded the train and began to question him. Fallon, according to one agent, was sweating and trembling, but denied that he was carrying weapons, drugs, or more than $10,000 in currency. Fallon allowed agents to search his duffle bag but declined to permit them to open his briefcase, which was locked. Fallon claimed to not have a key to open the briefcase, but admitted that it contained about $50,000, which he said was to purchase a house in Seattle. Agent Eric Romano said he was going to hold the briefcase for further investigation and directed Fallon to come with him off the train.

At the Amtrak police office, Romano called the Chicago Police Department and requested a drug-detection dog. In Fallon’s presence, Romano used a pocketknife to pry open the briefcase, and saw the bundles of currency. Fallon now said that the currency actually belonged to a third person with whom Fallon said he was going to invest in glass blowing and glass art.

Richard King, a canine officer with the Chicago Police Department arrived, and the DEA agents present told him they suspected the currency of being “narcotics transaction money.” Officer King was thus being advised that the drugs would quite likely result in an alert by his dog, precisely the situation that resulted in so many false alerts in the 2011 Davis study. Romano placed the briefcase in the roll-call room of the Amtrak police office, after which Officer King brought his drug detection dog, Deny, into the room and ordered him to search for drugs. Not surprisingly, Deny alerted to the briefcase and the DEA agents confiscated it. Deny had previously conducted drug sniffs in the roll-call room, though no illegal drugs or suspected currency had been in that room the day of this sniff.

Procedural History

The government initiated a civil forfeiture proceeding against the funds, and Fallon and another man, Nicholas Marrocco, filed a joint claim. Marrocco was the actual owner of the funds. Marrocco was not charged with any crimes and argued that the funds were the fruit of an illegal search and should be suppressed. The district court granted Marrocco’s motion, holding that the agents had had reasonable suspicion to hold the briefcase temporarily but lacked probable cause to open it prior to Deny’s alert. In 2009, the Seventh Circuit reversed, based on the inevitable discovery doctrine. U.S. v. Marrocco, 578 F.3d 627 (7th Cir. 2009).

On remand, the government filed a motion for summary judgment and Marrocco filed a motion to exclude any evidence concerning Deny’s alert to the briefcase. Marocco also requested a hearing to challenge evidence offered by the government purporting to establish that drug-dog alerts to currency demonstrate that the currency has recently been in contact with illegal drugs. The motion for a hearing was denied, and the government withdrew its motion for summary judgment but then filed another, to which Marrocco responded by arguing that drug-dog alerts to currency are generally unreliable, Deny’s training was inadequate, and the sniff was conducted in an unsound manner. Marrocco produced expert affidavits, which the government moved to strike. The district court denied the motion to strike but said that the government could challenge the expert evidence. The district court denied the government’s motion for summary judgment.

The government filed a third motion for summary judgment, arguing that the evidence established that the funds were either the proceeds of an illegal drug transaction or were intended to facilitate such a transaction, and listed four reasons that this was the case.
  1. Fallon fit a drug courier profile, apparently because he bought a one-way ticket and was nervous.
  2. Marrocco’s tax returns, W-2s, and deposition testimony revealed that his expenses exceeded his income for the previous four years, and that thus his legitimate sources of income were insufficient to explain the funds. It was not considered that many people have savings, and many borrow cash from relatives and friends.
  3. Records and affidavit testimony from King regarding Deny’s training, certification, and past field performance proved that Deny was a reliable drug dog.
  4. The methodology used in the drug sniff was sound.
In response, Marrocco argued that there were genuine issues of material fact regarding whether Marrocco had a legitimate source for the funds and the significance of Deny’s alert. The district court, however, granted the motion for summary judgment and Marrocco appealed.

Seventh Circuit Analysis

On the second appeal in the matter, the Seventh Circuit said that the government bore, under 18 U.S.C. 983(c)(1), a burden of proving by a preponderance of the evidence that the funds were either the proceeds of an illegal drug transaction or were intended to facilitate such a transaction. Under 18 U.S.C. 983(c)(3), the government had to established a substantial connection between the property to be forfeited and the criminal offense.

Marrocco argued again that there were genuine issues of material fact as to whether he had legitimately acquired the funds and whether Deny’s alert demonstrated that the currency had recently been in contact with illegal drugs. As to the first issue, the circuit court determined that the district court erred in finding as a matter of law that Marrocco could not have acquired the funds legally.

The Seventh Circuit then considered Marrocco’s argument that Deny’s alert did not establish that the funds had been in contact with illegal drugs because drug dog alerts to currency are generally unreliable, Deny’s training was inadequate, and the sniff was unsound.

Currency Contamination

Marrocco argued that significant amounts of U.S. currency are innocently contaminated with trace quantities of drugs, usually cocaine (chemically, benzoyl-methyl-ecgonine). The Seventh Circuit had accepted this argument in U.S. v $506,231 in U.S. Currency, 125 F.3d 442 (7th Cir. 1997), but had changed its position in 2005 in U.S. v. $30,670, relying largely on the research of Dr. Kenneth Furton. Dr. Furton had determined that, in the words of the current case, “drug dogs do not sniff cocaine per se, but rather methyl benzoate, which dissipates quickly.” The circuit court had thus ruled that drug dog alerts to currency are probative of illegal drug activity.

Marrocco offered the testimony of Dr. Sanford A. Angelos, a forensic chemist, who, in an affidavit, challenged the conclusions of Dr. Furton. Dr. Angelos (who died in 2011), cited a paper by Paul Waggoner, Canine Olfactory Sensitivity to Cocaine Hydrochloride and Methyl Benzoate, SPIE, 2937, 216-226, which found that drug dogs can alert to illicit cocaine samples with concentrations of methyl benzoate below their detection thresholds. Dr. Angelos also stated, according to the circuit court, “that, so long as cocaine is present on the currency, the cocaine will continue to generate methyl benzoate and thereby replenish the methyl benzoate lost to evaporation.” Dr. Angelos argued that cocaine residue can become trapped in currency and that the amounts of cocaine residue on currency assumed by Dr. Furton’s study might be incorrect. According to the court:

“The 1997 Furton study relied upon a study finding that circulated Canadian currency contained no more than 10 nanograms of cocaine. See J.C. Hudson, Analysis of Currency for Cocaine Contamination, 22 Can. Soc. Forensic Sci. J. 203–18 (1989). However, Angelos avers that other studies have found that significant amounts of circulated United States currency contain from 1 microgram (100 times as much cocaine as the Hudson study found) to over 1000 micrograms (100,000 times as much cocaine as the Hudson study found).”

Dr. Angelos noted that another of Dr. Furton’s studies dating from 1999 had posited a lower threshold at which dogs could detect methyl benzoate than had been stated in the 1997 research on which the Seventh Circuit had relied in U.S. v. $30,670 (1 to 10 micrograms in the later research, as against at least 10 micrograms in the earlier research). The circuit court noted that one study cited by Dr. Angelos might actually contradict his arguments:

“One of the studies upon which Angelos relies indicates that the amount of methyl benzoate produced will decrease over time. See Lindy E. Dejarme, et al., Formation of methyl benzoate from cocaine hydrochloride under different temperatures and humidities, 2937 Proceedings of SPIE 19, 21 (February 1997). Although we lack the advantage of expert testimony explaining this part of the study, it appears that the study found that ‘pure’ cocaine only continues to produce methyl benzoate for about 2880 minutes (that is, 48 hours) depending on the temperature and humidity conditions. If so, it is difficult to see how the Funds, which Marrocco claims to have saved from years earlier, could still be producing methyl benzoate based on cocaine that allegedly tainted the Funds before Marrocco acquired them. Further, this seems to conflict with Angelos's claim that cocaine remaining on currency for extended periods of time ‘will slowly break down and release methyl benzoate.’ Regardless, the proper interpretation of this study and the import of its findings can best be developed through expert testimony—perhaps at a Daubert hearing.”

The court did not discuss other possible sources of methyl benzoate that could have contaminated the currency Fallon was carrying, but this might be appropriate to consider in a Daubert hearing. This substance is used in many products including solvents, dye carriers, flavorings, and cosmetics, and can come from numerous sources.  If Fallon had stored certain items, such as lip balm, some sunscreen and hand creams, or enough of over 2,000 other substances in the briefcase with the cash, a possible source of transfer could be indicated. 

As to whether the Deny’s alert was probative of a substantial connection between the currency and illegal drug activity, the circuit court said that a genuine issue of material fact existed.

Currency No Long Available for Testing

The court noted that the funds were no longer available for testing because “[p]resumably the government deposited the Funds into a bank account.” The court noted that “Deny’s alert would be unnecessary if the government had used laboratory testing to determine whether the Funds contained amounts of cocaine in excess of the amounts reported in general-circulation currency. By failing to perform such testing (and failing to preserve the Funds until the conclusion of this proceeding), the government eliminated laboratory testing as a source of evidence.” Recent research, which will be mentioned below, may add to the significance of the failure to retain the actual currency for forensic purposes.

Deny’s Training and Performance

Officer King stated that Deny had received 500 hours of pre-certification training and was certified by the Chicago Police Department Training Division as a Police Utility Dog in July 1998. Most of Deny’s alerts in training were to actual drugs, not tainted currency. Dr. Lawrence J. Myers, a defense expert, “avers that there is no scientific evidence demonstrating that a drug dog’s ability to detect cocaine translates into the ability to detect cocaine residue on currency.”

Another defense expert, a dog trainer and behavior consultant, David Kroyer, according to the court:

“… states that the government's evidence regarding Deny's training indicates that Deny was not trained to distinguish between the odor of illicit cocaine and odors such as baking soda, vitamin B-12, and other agents used in creating or "cutting" the cocaine. Consequently, according to Kroyer, Deny's training likely (if mistakenly) instilled in him the tendency to alert not only to the odor of cocaine but also to odors of agents which are used in creating illegal cocaine (but which are not necessarily connected to illegal drugs).”

Dr. Myers and Kroyer stated that “it is industry standard to ‘proof’ a drug dog off of uncontaminated currency—that is, to ensure that the drug dog does not alert to uncontaminated currency.” Kroyer interpreted Deny’s records as indicating that the dog had once alerted to uncontaminated currency. These two witnesses said that it was industry standard to use an outside agency to certify a dog, but that Deny was only certified by the Chicago Police Department Training Division. Dr. Myers emphasized:

“[T]here was no evidence that Deny's training was performed under double-blind testing conditions. Dr. Myers explains that failing to use blind testing can result in ‘cueing’—that is, unconsciously signaling the drug dog to alert or not alert based on the handler's knowledge that the target of the sniff contains or does not contain drugs.”

The district court had held as a matter of law that Deny’s training and field performance established by a preponderance of the evidence that he was a reliable drug dog. That court had relied on U.S. v. Limares, 269 F.3d 794 (7th Cir. 2001), which had focused on the field statistics of the dog in question (Police and Military Dogs, 141, n. 38, 166, n. 6). The district court had determined that the evidence concerning deficiencies in Deny’s training was irrelevant because it suggested “that proof of Deny’s reliability requires something more than evidence of his performance in the field.” The Seventh Circuit, however, said that Limares was procedurally very different from the case at hand because Limares concerned whether there was sufficient evidence to issue a warrant based on probable cause in an ex parte proceeding, not on whether a dog is reliable in a civil forfeiture proceeding (which involves a higher burden of proof).

Florida v. Harris

This brought the Seventh Circuit to the point where it had to take the Supreme Court’s decision in Florida v. Harris into account. That decision had determined that courts should not treat “a dog’s field performance as the gold standard of evidence.” Instead, “evidence of a dog’s satisfactory performance in a certification or training program” is more probative. The circuit court said that the “Supreme Court specifically envisioned attacks on the drug dog’s training.” The court also stated that “[i]f Deny did alert to untainted currency during one of the three times he was tested, then that fact ... could cause a trier of fact to doubt Deny’s reliability.”

“Similarly, Kroyer avers that a drug dog trained on illicit street cocaine rather than pure pseudo-cocaine must be proofed off of the odors of the agents used in creating or ‘cutting’ cocaine (for example, baking soda or vitamin B-12) to ensure that the dog can distinguish cocaine from these other odors. King states that Deny was trained with currency tainted by illegal drugs. And the training log indicates that Deny was not proofed off of the odors of the agents commonly used in ‘cutting’ cocaine (but which are common household products) because the log contains all of Deny's pre-certification training searches and none of the entries involve testing Deny against any of the agents used in ‘cutting’ the cocaine. Thus, Kroyer's averments on this issue provide an additional reason to think that Deny's training was inadequate.”

The circuit court concluded that the fact Deny was certified in-house by the Chicago Police Department might not be sufficient by itself to dispute reliability, it had some significance when combined with the other reliability issues raised.

Cueing and False Alerts

Dr. Angelos, in his affidavit, stated that Deny may have been cued or the briefcase may have become contaminated at the train station. The circuit court said that Marrocco had produced no evidence that the roll-call room was contaminated with enough cocaine to trigger a drug-dog alert. The court cited McCoy v. Harrison, 341 F.3d 600 (7th Cir. 2003), as well as U.S. v. $30,670, as establishing that the mere possibility of cross-contamination does not deprive a dog’s alert of probative weight. The circuit court noted conflicting evidence with regard to where the briefcase was during the sniff in the roll-call room, but said that this issue “can be explored more thoroughly on remand,” presumably in the Daubert hearing already suggested as appropriate for the district court to hold.

Recent Forensics Research

Four scientists at the University of Central Oklahoma and Oklahoma State University quantified cocaine contamination on bills of different denominations using gas chromatography/mass spectrometry or liquid chromatography/mass spectrometry. They looked at bills from three sources:
  • questioned bills in criminal cases
  • control bills
  • uncirculated bills received directly from the Bureau of Engraving and Printing (BEP).
Uncirculated bills received from BEP produced readings lower than the administrative limit of detection. Approximately 97% of bills in general circulation in the U.S. “demonstrated quantifiable levels of cocaine residue,” probably due to mechanical currency counters. Bills were obtained from 66 cities in 43 states and the District of Columbia. The national average was determined to be 2.34 ± 0.08 nanograms (ng) per bill. Distribution across denominations was “reasonably uniform,” which the researchers found consistent with currency counters being a mechanism of spreading cocaine residue.

The researchers noted that it “is unlikely that members of the illicit drug trade have actually physically handled the number of bills that are currently circulating with cocaine contamination.” One means of contamination comes from the use of mechanical currency counters employed in retail and financial institutions which have a “homogenizing” effect on the trace contaminants in the money supply. This was first noticed in 1993 when uncirculated bills from a teller’s drawer at a bank in West Columbia, Texas, were found to have high contamination levels. After it was determined that the bills had been counted by the bank’s mechanical currency counter, the interior of the counter was swiped, and the swipe generated “a massive cocaine peak” in a plasmagram. The researchers found that “a single exposure to a contaminated currency counter will contaminate the bills to the ambient level.”

Variations were detectible between nearby locations. Manhattan had levels more than twice as high as New Hyde Park, New York (0.812 ng/bill vs. 0.334 ng/bill); Miami had levels more than twice as high as Fort Lauderdale (2.83 ng/bill vs. 0.102 ng/bill); El Segundo, California had levels almost 15 times as high as Downey, California (11.5 ng/bill vs. 0.784 ng/bill). Bill specimens coming to the FBI Laboratory’s Chemistry and Toxicology Unit from 1993 to 2001, by comparison, assayed in the area of 80 ng/bill. A bill that shows a sufficiently high degree of contamination may possibly be associated with illicit drug trafficking.

This means that in addition to using a drug dog to assess whether cocaine may have been associated with the drug trade, prosecutors will want to assay the level of cocaine on bills before deciding whether to begin a forfeiture proceeding. The chemical technology used in this study will be combined with research on canine forensics in various ways to establish optimal procedures for forfeitures and prosecutions. The chemical research also creates possible defense strategies. If the defense can establish that the bills were obtained recently from a bank, the defense may want to have any currency counter that may have been used tested for cocaine contamination.

Thomas H. Jourdan, Allison M. Veitenheimer, Cynthia K. Murray, and Jarrad R. Wagner (2013). The Quantification of Cocaine on U.S. Currency: Survey and Significance of the Levels of Contamination. Journal of Forensic Sciences, 58(3), 616-624.

Another interesting research article that also appeared in the Journal of Forensic Sciences found that residues of amphetamine derivatives, opiates, and benzodiazapines could be detected on Euro banknotes. A Spanish research team found that a “procedure based upon extraction with organic solvent, liquid chromatography separation, and mass spectrometric detection allowed the identification of 21 drugs and metabolites in 120 used Euro banknotes collected in the Canary Islands.” This also will necessarily become an area of further research to determine whether amounts of other drugs detected can indicate anything more about the source of the contamination.

Octavio P. Luzardo, Maira Almeida, Manuel Zumbado, and Luis D. Boada (2011). Occurrence of Contamination by Controlled Substances in Euro Banknotes from the Spanish Archipelago of the Canary Islands. Journal of Forensic Sciences, 56(6), 1588-1593.

Other research described at a meeting of the American Chemical Society found that contamination levels of banknotes are increasing, so what is considered background will have to be adjusted depending on when a sample is collected. For a summary of numerous studies concerning cocaine concentrations on currency up to 2002, see Charles Mesloh, Mark Henych, and Ross Wolf (2002). Utilization of the Law Enforcement Canine in the Seizure of Paper Currency. Journal of Forensic Identification, 56(6), 704-724.


The Seventh Circuit is probably correct that attacking a detection dog's reliability after U.S. v. Harris will require looking closely at training and certification, with less emphasis on field performance.  In-house certifications of the sort provided by the Chicago Police Department will be suspect, as those providing the certification may have reasons to assure that an adequate number of dogs are in the field. Training that does not assure that a dog can distinguish contaminated currency from uncontaminated currency, and distinguish currency from various items that can produce methyl benzoate residues, will raise significant questions about deploying a dog in situations such as Deny faced at the train station.  This also will likely be a significant issue in further proceedings in this case.

On the other hand, if a dog's performance in the field can be correlated with specific amounts of drug residue on an item, such as currency, then this is no longer, for purposes of a U.S. v. Harris analysis, identical to the situation where a dog's alert may be to residual odor, minute amounts of a drug, or just a false or cued alert.  If the amount of drugs on currency can be measured and compared with the threshold of the dog's capacity to recognize the drug, then surely this becomes the sort of situation where, in the words of Justice Kagan, "the dog's (or handler's) history in the field ... may sometimes be relevant...."  This remains true even if the instability of methyl benzoate must be taken into account in analyzing the dog's performance.   

If the dog alerts, but the cocaine residue on the bills is average for the area in which the currency was found, then the defense has an argument that methyl benzoate may have come from another source than as a byproduct from cocaine.  If the dog alerts and the bills have significantly more cocaine than most bills in circulation in the area, then the prosecution has reinforced its case that the currency had a connection to the drug trade.  If the dog does not alert, but the currency has high levels of cocaine residue, then the holder of the currency can still be connected to the drug trade if he or she held the currency long enough and other sources of contamination are ruled out.

As noted above, testing the currency in $100,120 is no longer possible because it was deposited into an account and entered general circulation. Any law enforcement official who does this in the future ought to have his head examined as defense counsel will be quick to point out that this is effectively destroying evidence.  A dog’s alert can be reinforced by the chemical analysis, or undermined, but both approaches should be considered in the future.

This blog was written by John Ensminger and L.E. Papet.

Monday, September 9, 2013

Pointing Gestures and False Alerts: Recent Research Suggests How Dogs May Turn into Walking Search Warrants

Publication Note:  A law review article on  Florida v. Harris, written by L.E. Papet and me, has been posted on the website of the Michigan State University Animal Legal and Historical Center. The article makes use of the same phrase, walking search warrants, which we first published here.  The article was the lead in the 2014 issue of the Journal of Animal and Natural Resource Law, a refereed journal of Michigan State University.  Walking Search Warrants: Canine Forensics and Police Culture after Florida v. Harris.

Eighteen police dog teams entered a church where there were no drugs, and where residual odors were unlikely, yet 17 of the 18 teams alerted to the presence of target odors, most multiple times.  In a paper that caused a good deal of consternation in the police dog world, three scientists at the University of California at Davis argued that the false alerts arose from the fact that the police dog handlers had been led to believe that there were drugs inside the church.  The handlers had cued their dogs.  The results were not videotaped and the authors of the paper did not state exactly how the dogs had been induced to alert when their training should have prevented this.  Recent research on human pointing gestures and dog responses goes some way towards explaining how this may have happened. 

In order that drug dogs not become walking search warrants—as an Ohio deputy sheriff described his dog in a recent newspaper article—it is important that supervisors, handlers, and lawyers understand this research and consider its implications. 

Detailed Sweeps  

Handlers of drug dogs take them into areas where drugs may be present and often want to focus the attention of a dog on a particular place where drugs may be hidden by using a “detailed sweep.”  The dogs are trained to alert to the odor of specific drugs and that behavior involves the dog exhibiting a trained final response, such as sitting and staring, which the dog was initially trained to do in order to receive a reward if a target odor is in fact present.  A problem arises if the dog anticipates the reward or interprets the handler’s behavior, either by subtle suggestion or overt command, and demonstrates the trained final response regardless of the presence of any target odor.  (For a general discussion of cueing, see Cueing and Probable Cause, a periodically updated electronic article on the website of the Animal Legal and Historical Center of the Michigan State University College of Law.)

If the handler uses pointing gestures to direct the dog’s attention to a particular location, which is routinely done in detailed sweeps, the question then becomes whether the dog uses that information solely as a direction to smell in an area, or if the gesture itself is being interpreted in part as a command to alert.  In the latter event, the dog has been cued, and the alert should not provide probable cause for any subsequent investigation by the police who are present.  A recent study published in Animal Cognition tells us something about this complex issue, and it is worth the attention of both police dog handlers and lawyers involved in drug cases where dogs were part of the process by which the drugs were found. 

Dogs React to Pointing Gestures

A person hides a reward in one of two identical cups.  A dog enters the room where the food has been hidden and the person points at one of the cups.  Dogs, more often than any other species that has been tested, will go towards the cup which the person is pointing at, more than chimpanzees, our closest living relative, and more than wolves, of which dogs are a subspecies. By six weeks of age, puppies can follow a human pointing gesture even if this means moving away from the human’s hand.  Four scientists at the Max-Planck Institute for Evolutionary Biology in Leipzig, Germany, describe this skill as special and evidence that “selection pressures during domestication may have affected dogs’ ability to use human communication.” 

But do dogs see a human pointing gesture as “an informative communicative act” or as a command?  The four scientists, Linda Scheider, Juliane Kaminski, Josep Call, and Michael Tomasello, in a paper published in the scientific journal, Animal Cognition, designed an experiment to try to answer this question.  They did not reach a definitive conclusion, but their findings advance the debate and are worth careful consideration.   

Earlier Study Where Dogs Ignored Their Noses

In 2003, another team of scientists from the Department of Ethology of Eötvös Lóránd University in Budapest, had found that when confronted with a choice of two bowls, dogs could ignore their own better knowledge and follow the pointing gesture of a human.  One bowl contained strong-smelling food, potent enough for the dog to be able to smell it from its starting position.  The other bowl was empty. In 79% of cases dogs followed the pointing gesture, suggesting to that team that they were interpreting the pointing as a command. The Hungarian team concluded:

“In the case of contradictory cues, dogs prefer to rely on the human communicative signaling (pointing) when they have only olfactory information about the hiding place. Their willingness to do this decreases, however, if they themselves are in the position to obtain visual information about the ‘state of the world’. This means that if a dog sees where the food is placed, it is more reluctant to go in the opposite direction pointed at by the human, even if they had some ever-day experience (with their owner for example) that pointing strongly correlates with the presence of food. This suggests that dogs do not follow human pointing blindly; they seem to have some control over their response to the pointing gesture. However, it is interesting to note that in both studies about half of dogs in these experimental groups seem to fall in either the two following categories. Some dogs mostly ‘believed’ their own eyes, whilst others would go to the empty bowl indicated by the pointing. This also suggests that, possibly due to social experience for some dogs, human pointing becomes one of the most reliable sources of information in the environment.”

This suggests that in choosing dogs to train for detection work, an effort should be made to find dogs that “believe their own eyes.”  This earlier research, it is worth noting, included Ádam Miklósi, perhaps the most important animal behaviorist currently working on canine cognition.    

Experiment 1

The team from the Max-Planck Institute devised two experiments.  In the first, 96, 50 females and 46 males, of various breeds were used.  Dogs were pets and ranged from 1 to 13 years.  To ensure that dogs could make only one choice, even when a human was not present, cups were placed in a long Plexiglas box with an opening to a compartment at each end.  There was a distance of 1.2 meters between openings.  A sliding cover had to be moved to reach the cup inside the compartment, and once moved the other opening was closed, confining the dog to one choice per trial. 

The experimenter, a 27-year-old woman, caught a dog’s attention by clicking her tongue, then baited one of the cups in full view of the dog so that the dog would get used to the idea that there would be food during subsequent trials.  If the dog chose the correct cup, it was allowed to eat the food.  If it chose the wrong cup, it got no reward.  Food was hidden on both sides so that the dog would know that there were two possible locations for food. 

Dogs were divided into groups where the experimenter made the pointing gesture but added no ostensive cues, and those for whom the experimenter would say things like “Luna, pass’ mal auf; pass’ auf, Luna!” =, in English: “Luna, pay attention; pay attention, Luna!” The procedure that followed this action depended on four conditions: 
  1. Authority leaves: dog knowledgeable. After baiting a cup but pointing to the empty cup, the experimenter left the room and the helper let the dog go. The dog had one minute to choose.
  2. Authority leaves: dog ignorant. The experimenter showed the dog a piece of food but the helper closed a curtain so that the dog could not see the experimenter putting the food in one of the cups.  The experimenter pretended to bait the second cup to eliminate the chance that the dog would receive audible information.  The helper opened the curtain and the experimenter pointed.  Again the dog had a minute to choose.
  3. Authority stays: dog knowledgeable.  This was the same as the first trial, but the experimenter remained in the room after pointing, standing motionless with arms hanging down, head bowed, eyes open.
  4. Authority stays: dog ignorant.  This was the same as the second trial except the experimenter remained. 
Dogs followed the pointing gesture to the empty cup significantly more if they did not know the real location of the food.  When they had seen the cup being baited, they generally relied on their visual experience and chose the baited cup, ignoring the pointing gesture.  Whether or not the experimenter—the pointer—remained present when the choice was made had no effect on the dogs.  Nevertheless, if the experimenter pointed, they made the wrong choice significantly more often (about 30% of the time) than in the control condition, where the experimenter did not point.  The use of the additional verbal cues, such as the words of encouragement, did not significantly alter the results.  The fact dogs followed the pointing gesture 30% of the time, when they should have known where the food was, indicated to the researchers that dogs may indeed “interpret pointing to some extent as a command.” This, it should be noted, is a reason for using more than a few blank trials in training regimens, as a dog's taking of pointing as a command to alert will not be apparent without a sufficient amount of testing. 

Experiment 2

In the second experiment of the Max-Planck team, the authority of the human pointing was varied.  “Authority,” according to the team’s definition, was “a person who is able to control the behavior of dogs in a directive way.”  Thus, sometimes the pointer was an adult, sometimes a child.  If pointing is a command, adults should be obeyed more often.  If pointing is informative, it should not matter who is doing it. 

Here, the person pointing could be an adult female or a boy or girl between 4½ and 5½ years old.  Some of the pointing was “honest,” meaning that the experimenter pointed to the cup with food, and sometimes “deceptive,” with the experimenter pointing to the cup without food.  In honest trials, the dog did not witness the cup being bated.  In deceptive trials, dogs witnessed the baiting and knew where the food was. 

Forty-six dogs participated in these trials.  The researchers recruited 26 mother-child pairs as experimenters, none of which had major contact with the dogs before.  Of the children, 15 were girls and 11 boys.  For safety reasons, both children and adults were separated from the dogs by a Plexiglas wall.  Two opaque plastic cups were placed on a wooden board with a distance of 1.3 meters between them.  Most mother-child pairs tested two dogs. 

The researchers found that the dogs “did not differentiate between children’s and adults’ pointing gestures.  The dogs followed the pointing gesture and found the food irrespective of the authority level of the person pointing.”  Nevertheless, when given explicit commands by adults and children to sit, the dogs largely ignored commands by children.  This suggests, according to the researchers “that dogs do not interpret pointing as a strong command comparable to a command like, e.g., ‘sit’.”  This means that anyone analyzing whether a narcotics detection dog is being cued by a handler’s pointing gestures should not expect results as automatic as when a dog sits, stands, or lies down on command.  This also argues that, in establishing testing regimens (whether during training or for certification), there should be a significant number of blank trials in which no target odor is present, as a small number of trials may not reveal a tendency on the part of a dog to alert as a result of pointing gestures.  

Significance of the Research for Cueing Issues in Criminal Trials

The Max-Planck research team concludes that “pointing is a gesture that dogs mainly choose to ignore in situations in which they have better knowledge.”  Not all their results indicated that dogs ignore their own senses when a human’s pointing gesture would lead them to an empty cup.  Thus, their results were not as stark in finding that pointing overcomes knowledge as were the 2003 results of Szetei et al., which the current researchers say might be due to the fact that the earlier research involved both olfactory and visual modalities, while their research “exclusively addressed the visual modality. Seeing food and then following another visual stimulus (the gesture) to an alternative location may be more difficult than smelling the food and then following a cue based in another modality, i.e., visual.”  This observation is important for cueing arguments regarding narcotics detection dogs in that it suggests that pointing may overcome a dog’s reliance on its sense of smell even more than its sense of sight.  Ideally, a narcotics detection dog should not allow a pointing gesture to induce a trained response that is supposed to be solely to a smell—the dog’s alert, yet with a dog that has begun to rely too much on a handler’s pointing gestures, this may be exactly what is happening. 

These behavioral studies used pet dogs that had not been subjected to rigorous scent specific training.  They had not been required to undergo repetitive activities involving pointing, particularly frequent in the early stages of drug dog training.  Such instructional pointing is used in part as a command for the dog to smell in a certain area, but it is important that it not become a command to exhibit the behavior that indicates the presence of drugs.  (For a series of still photographs showing how a pointing gesture can be easily turned into a command, see Ensminger and Papet (2011).  How to Prevent Cueing Arguments from Getting Canine Evidence Thrown Out in Court.  Deputy and Court Officer, 3(2), 36-39.  Unfortunately, it does not appear that the photographs associated with our article are available online so a library copy will have to be obtained, or it may be available from personnel in some courthouses.) 

If a drug dog goes where directed, but does not alert without smelling the odor of drugs, then there is no harm. The question then becomes, for an officer trying to assure the reliability of his dog, or a defense counsel trying to attack the alert of a drug dog, whether the dog tends to alert more often when there is a pointing gesture than when there is not, and to have false positives that cannot be so easily explained away by residual odors.  This requires that there be accurate training records, and that those records involve a significant number of blank trials. (Field records may also be helpful, such as when compiling overall statistics and in comparing teams over significant periods of time.) 

Cueing and the U.S. Supreme Court

The concept of cueing is mentioned in the Supreme Court’s decision in Harris, where Justice Kagan states that “even assuming a dog is generally reliable, circumstances surrounding a particular alert may undermine the case for probable cause—if, say the officer cued the dog (consciously or not), or if the team was working under unfamiliar conditions.”  Among things that defense counsel should look for are indications that pointing has, for a dog, become more than informative, that it has become a command that the dog alert. 

Justice Kagan said that a defendant “must have an opportunity to challenge such evidence of a dog’s reliability [from certification or training programs], whether by cross-examining the testifying officer or by introducing his own fact or expert witnesses.” Professor Andrew Taslitz recently argued—correctly in our opinion—that the Court’s reference to expert testimony can “be read to include expert scientific testimony, and the risk of cuing is indeed one about which the science of dog detection warns.” Such studies as the ones described here are therefore important for counsel to consider in developing defense arguments.  (Professor Taslitz’s recent article appears in the American Bar Association’s publication, Criminal Justice, and may be downloaded from the magazine’s website.)


Fortunately for those who wish to determine a possible propensity for alerting because of a handler’s conscious or unconscious signals, more is now being learned about canine responses to human behavior patterns.  We will be adding a number of important behavioral studies to our running article on Cueing and Probable Cause that are significant in this connection.  We are also writing an analysis of Harris and Jardines where we will discuss the impact the Supreme Court’s decisions are likely to have on police practices and culture. Meanwhile, research such as that discussed here provides important guidance for supervisors concerned with handlers whose dogs’ alerts are too often leading to pointless investigations, and defense counsel who want to question whether a dog was reliable enough to base probable cause on its alert.   

  1. Lit, L., Schweitzer, J.B., and Oberbauer, A.M. (2011).  Handler Beliefs Affect Scent Detection Dog Outcomes. Animal Cognition, 14(3), 387-394.
  2. Scheider, L., Kaminski, J., Call, J., and Tomasello, M. (2013). Do Domestic Dogs Interpret Pointing as a Command?  Animal Cognition, 16(3), 361-372.
  3. Szetei, V., Miklósi, A., Topal, J., and Csanyi, V. (2003).  When Dogs Seem to Lose Their Nose: An Investigation on the Use of Visual and Olfactory Cues in Communicative Context Between Dog and Owner.  Applied Animal Behaviour Science, 83(2), 141-152.
  4. Taslitz, A.E. (Summer 2013). The Cold Nose Might Actually Know?  Science and Scent Lineups.  Criminal Justice, 28(2), 4-8, 55-7.
 This blog was written by John Ensminger and L.E. Papet. 

Thursday, September 5, 2013

Fish & Wildlife Announces Public Hearings on Taking Gray Wolves off the Endangered List

Additional Hearing Announced.   In the October 2, 2013 Federal Register, the Fish and Wildlife Service announced that it will hold an additional public hearing on October 17, 2013, in Denver, Colorado. The hearing will be held at the Paramount Theatre, 1621 Glenarm Place in Denver.  A phone number is listed: (303) 405-1245.  A call to this number was answered by a machine explaining that I had reached the Kroenke Sports Events and Entertainment Department. 78 Fed. Reg. 60813 (October 2, 2013)  

The U.S. Fish and Wildife Service has extended the comment period on its proposals to remove the gray wolf from the List of Endangered and Threatened Wildlife but to keep the Mexican wolf listed as endangered.  The comment period was due to end on September 11, but is now being extended to October 28.  Three public hearings have been announced on these proposals:
  • September 30, 2013, from 6 pm to 8:30 pm in Washington, DC, at the Department of the Interior Auditorium, 1849 C Street, NW.  For building information call: (202) 208-3100.
  • October 2, 2013, from 6 pm to 8:30 pm in Sacramento, California, at the Clarion Inn, Martinique Ball Room, 1401 Arden Way, Sacramento, California 95815.  For location information call: (916) 922-8041.
  • October 4, 2013, from 6 pm to 9 pm in Albuquerque, New Mexico, at the Embassy Suites, Sandia Room, 1000 Woodward Place NE.  For location information, call (505) 245-7100.
Apparently only the third hearing will consider the remaining protection on the Mexican wolf. The extension of the comment periods and the public hearings were announced in the Federal Register on September 5.
For anyone who has not commented yet, written comments will be accepted by Fish and Wildlife Service personnel at the meetings. If you want to speak at one of these hearings, the Service states the following:

“We are holding the public hearings to provide interested parties an opportunity to present verbal testimony (formal, oral comments) or written comments regarding the June 13, 2013 (78 FR 35664), proposal to remove the gray wolf from the List and maintain protections for the Mexican wolf by listing it as endangered. A public hearing is not, however, an opportunity for dialogue with the Service or its contractors; it is a forum for accepting formal verbal testimony. Anyone wishing to make an oral statement at the public hearings for the record is encouraged to provide a written copy of their statement to us at the hearings. In the event there is a large attendance, the time allotted for oral statements may be limited. Speakers can sign up at the hearings if they desire to make an oral statement. Oral and written statements receive equal consideration. There are no limits on the length of written comments submitted to us.”

So don’t expect the Fish and Wildlife officials on hand to do anything more than listen (particularly if it gets heated).