Study: Drug Dogs Most Likely To Err In Traffic Stop Scenarios

Dogs trained to detect the presence of illegal drugs are most likely to provide false alerts in situations involving the search of a motor vehicle, according to the findings of a study published online in the journal Forensic Science International.

A team of researchers from the United States and Poland assessed the ability of trained drug sniffing dogs to accurately detect the presence controlled substances – including marijuana, hashish, amphetamines, cocaine and heroin – in various environments.

Dogs were most likely to correctly identify the presence of contraband, particularly marijuana, during searches of individual rooms. If the dog had previous exposure to the room prior to the search, it was least likely to provide a false alert (83 percent correct identifications versus 10 percent false alerts).

Dogs were far less reliable in scenarios designed to mimic real-world traffic stops. In situations where dogs accessed the perimeter of a motor vehicle, the animals accurately alerted to the presence contraband only 64 percent of the time. Fifteen percent of the time dogs failed to recognize the presence of illicit drugs. Twenty-two percent of the time the dogs indicated that illegal drugs were present when they were not.

Drug dogs’ failure rates were even more pronounced in situations where the animals had access to the inside of a vehicle. In this scenario, dogs correctly responded to the presence of contraband only 58 percent of time. They provided false alerts 36 percent of time.

Previous studies have similarly documented drug dogs’ tendency to provide false alerts. In 2011, researchers at the University of California at Davis reported that the performance of drug-sniffing dogs is significantly influenced by whether or not their handlers believe illicit substances are present. That same year, a review of Australian government statistics, published in the Sydney Morning Herald, found that some 80 percent of drug dog alerts in New South Wales yielded no illicit substances.

In 2005, the United States Supreme Court ruled in Illinois v Caballes that an alert from a police dog during a traffic stop provides a constitutional basis for law enforcement to search the interior of the vehicle.

30 thoughts

  1. Where’s McGruff? The dog who takes “a bite out of crime.” We got bears who fight fires. Smokey. And eagles who spread freedom. Cats get high on catnip, we should be allowed to feel good by law. God put Marijuana here for a reason. And he saw that it was good. Stop the suffering and create jobs and make money. Jesus could have participated in some bowl passing. You can’t prove me wrong! 🙂 Legalize it!

  2. Note* during a traffic stop where dogs are not deployed ahead of time, the nazi pigs have to get the dog on site in 9 minutes under current court rulings of de minimus. (Sp). Know your rights and assert them!

  3. The dogs probably just smell the joint you smoked in your car last week. Police usually carry byob pot to plant on anyone they want to arrest anyway.

  4. If a drug dog cant tell the difference between pending or cold evidence does it really make a bark?

  5. “The infallible dog, however, is a creature of legal fiction…. Their supposed infallibility is belied by judicial opinions describing well-trained animals sniffing and alerting with less than perfect accuracy, whether owing to errors by their handlers, the limitations of the dogs themselves, or even the pervasive contamination of currency by cocaine.”
    — Justice Souter

  6. Drug dogs, dope dogs, whatever dogs. Not sure there’s point here, or there. Dogs want to make their people happy, even if that means pretending there are drugs. The dogs are only as good as their handlers. Pigs are much better than dogs, I don’t even understand why dogs are used, its just bullshit.

  7. The big problem is that these drug dogs can also alert upon hand signals from their handler who wants the dog to alert so that a search can be made. Our constitutional rights are going to hell.

  8. The title of this article is misleading. Considering the drug dogs gave false alerts 22% of the time, I wouldn’t say that’s “most likely”. It is more probable that the dogs will be right based on the info you gave.

    [Paul Armentano responds: Among the different scenarios the dogs were most likely to false alert in those mimicking traffic stops, as opposed to the other environments.]

  9. I like the idea of pigs, can’t you just see a pigs head sticking out a cop cars window!!!

  10. I’ll state it again…this title is misleading. The dogs are not giving false alerts more than 50% of the time so how can you say “most likely” to err? I’m all about legalization but I’m also about honest and accurate reporting

  11. I think we should all intentionally make our cars smell like weed but not carry any with us. If a lot of us did this, it would make their canine squad useless 🙂

  12. @Genius: I wouldn’t want to be one of that 22% of people who get stopped. That’s like those people who say “so what if drug testing produces false positive 30% of the time (National Workrights Institute study)–it’s still right over 50% of the time!” Well, how would you like to be the lucky guy or girl in that 30% who loses his job or goes back to jail for that false positive?

    Not to mention the fact that, as Souter was quoted saying in above comments, they can’t even tell the difference between actual cocaine and the scent of cocaine on that twenty in your pocket–and I’m sure lots of our money has drug smell on it, since drug users/dealers have to deal entirely in cash.

    You might say “oh, who cares, after all, if I’m not using/carrying drugs, I haven nothing to fear?” Well, think again. Remember that poor schmuck who was pulled over for not stopping completely at a stop sign in a private parking lot, and the cop assumed he had drugs in his butt because he was clenching his cheeks, and it resulted in several hours of medical torture, as they tried to forcibly extract the drugs that weren’t even there? Remember how that happened to about two other people I’ve heard of, one of them a woman?

    If you have nothing to hide, you have nothing to fear, indeed. That is one of the chief mantras of all of history’s tyrants and their useful idiots.

    Not to mention that the dogs often react not to whether there are drugs but whether the handler believes there are drugs, and the issue of handlers signalling the dogs to alert for someone they want to arrest. That, I’m sure, is a factor that, if added to that simulated number of 22% failure, would make that number even more significant. I wouldn’t want to be one of those poor people who ends up getting arrested for weed because of a drug dog alerting at a hand-command and the cops “finding” weed in my car, because they want to up their drug arrests, since we’ve linked that to how much money their police station gets.

  13. Wow, you know NORML, 50% would be the cut off, not 35% percent… Or maybe you don’t know…?

    The police have known pigs are much better at small searches than are dogs for over twenty years. I think they do not want to use pigs simply because they already get called pigs and it would make the association too great for the average person. “Here are the pigs with their pigs”.

    Now Genius, the dogs are the best at finding marijuana–they aren’t so good at finding real drugs, like cocaine and smack. And if you delete marijuana from their “success at finding drugs (that aren’t drugs)” then it is basically a 50% failure rate. Drug Dogs find marijuana a lot better than they do find drugs. Now that is funny. And does show how stupid this is. The courts are only upholding this crime because they dogs are good at find marijuana. If not for the inclusion of smelly marijuana, the dogs would probably already be something the police could not use.

  14. my so and a friend were stopped in OKlahoma. for not using a turn signal. then the called out the dogs now they are in jail for 4 oz of medical marijuana. the lawyer wants $17,000. please help if you can.

    Laws are changing in this country but not fast enough. Colorado has legalized pot and Washington is soon to follow but in Oklahoma a person can loose 2 years of their life for just possessing it. Oklahoma is where my brother is being held because his friend bought pot…Oklahoma is where my 22 year old brother is facing 10-20 years minimum mandatory sentence because His Friend bought Marijuana.

    My brothers name is Niccolo Artino, he is an Ohioan and its been his life’s goal to serve our community as a firefighter. He is in danger of losing that dream and his life to prison. Niccolo has tested clean of all substance and has the support of our family and community leaders. Please help our family save him and show that Justice can work for the Working Class.

    All funds raised will go to Niccolos defense. The Artino family thanks you for your support

  15. @ Dave Evans – I’ve never heard of NarcScent. But, I think we’re talking about the same thing in general 🙂 Anything to throw the prohibitionists off their destructive path!

  16. Jesus Christ!!! People stop trying to move marijuana across statelines for Christ’s Sake! These just want to abuse people and punish you for doing nothing wrong. When can we start arresting the pigs for wasting our money??? It really isn’t going to be safe for normal people until at least some of these pigs are being arrested for violating people’s rights. “You can’t have medicine that works for you because we own the meaning of the word medicine is not a legal argument in this country”. By our laws, there is no need for marijuana to be proven safe by the FDA as it is already known to be non-toxic. The FDA only had the right to regulate “dangerous materials” otherwise they need to get the hell outta the way. For example, someone is putting poison on marijuana and selling, then the FDA or DEA should arrest them. Why the hell are they arresting people for growing marijuana and selling clean marijuana. They are fucking crazy.

  17. First I have to say is, the law enforcement officer has to pull you over for some kind of driving violation. If the officer suspects that you may, key word may, have drugs he/she has to complete the original reason for the stop. By either giving you a ticket or warning. After that is completed you need to ask “am I free to go?” If not ask the why? If they say because they believe you may be in possession of drugs. Ask them why they believe that or what is there probable cause. Make them explain their reasons for detaining you because the original reason they pulled you over is done. Make sure you also take note of the time the officer gives you the ticket/warning or tells you can’t leave.

    As far as the dog concerns. Until something is done about the “Ambient Air” clause around the vehicles it will be difficult to fight. But how does the dog know if there was some possible residue somewhere around the vehicle from someone else.

    All ways remember if they ask for consent to search your vehicle say “NO”. The officer will always try to convince you to let them search by possibly saying “If you got nothing in there what do you have to worry about us searching the vehicle.” If you’ve said no make sure to continue to say no and try to remember all the times the officer tryed to convince you other wise.

    If you end up in court. You can challenge the dogs accuracy. That means they need to provide you all training records for the dog. This will tell you how many false alerts the dog has had. You can then figure out a percentage rate for the dog.

    Check your state to see if they require the officer and dog to be certified. If they are, see if their certification has lapsed. This could help your case because the wasn’t technically able to do the search.

  18. @Dustin,
    Thanks for the good defensive advice, but have you ever heard of the DEA’s Special Operations Division? The DEA has been using NSA phone records to seek vehicles for “traffick violations” using state troopers. They don’t even need a drug dog, much less a judge’s signature to fabricate evidence or use “parallel construction” to cover the paper trail. The new “guidelines” from the DOJ suggest to prosecutors they should omit the amounts one is arrested in posession of to keep mandatory minimums from taking effect. Governor Perry even passed a law 6 years ago that “suggests” to decriminalize a variety of crimes, including posessions of marijuana under 2 ounces. But without forcing the law to take effect, and with the profit incentives of law enforcement from asset forfeitures, overtime and promotions from non violent marijuana arrests, guess how many Texas counties have taken Perry’s political candy into effect? You guessed it: zero. Just like the number of marijuana related deaths in all human history or the number of U.S. Prisons that are drug-free; ZERO.
    Another problem is most U.S. Counties have no medical examiner, and if they do have a so-called lab or “forensic expert” they too are paid off by the DEA and prosecutors to close and convict drug cases. So much so that cities like Oakland California examen %90 of their drug cases and next to no DNA testing to solve rapes and murders. As a result, rapes and murders get backlogged so even if DNA evidence could later acquit someone on death row, the cases are cold and disorganized to the point where prosecutors cant even FIND the evidence! They dont know which cases are cold or pending.
    Angry yet?
    Here’s the catch to the SOD program: its written in the DEAs budget, but Congress doesn’t read that or they get paid off. And before Snowden and all this NSA stuff blew up the only way a good prosecutor can find out that evidence has been withheld and the defendent has been set up by fabricated evidence is if the defendent appeals his case. But no one appeals. Because the DEA threatens 10 to LIFE using trumped up conspiracy 1 charges if they appeal.
    The U.S. Imprisons more innocent people than China and Russia combined.

    When I was 21 I was once pulled over for a “dirty license plate.” After I repeatedly told the officer I didnt have marijuana, he finally let me go. Funny thing, I was drunk.

    The DEA has been using drug courts in Texas and secret FISA courts nationaly to keep unjust drug cases out of the books and view of decent judges. Good judges are forced to silence by law, unable to speak about the illegal activities of bad judges while they are actively licensed and the case is still pending. Bad judges receive kickbacks from the DEA through “campaign donations” for closing drug cases. They receive more kickbacks from private prisons and detention centers so they can maintain million-dollar federal contracts by maintaining %90 capacity quotas. Governors get these kickbacks, or bribes as well.
    We need to legalize marijuana at every local level of our “justice” system, so we can even claim we have justice. Thank God its finally happening.

  19. @Dave,
    Please stop using the word “nigger” –a racially loaded epithet– to divulge your rage on corrupt law enforcement. “Pigs” works fine, (although discriminatory against well behaved pigs).
    We are talking about bad cops, attorney generals, governors, judges and prosecutors trained by incentive from a bad “justice” system of bad drug policies.
    There are some good law enforcers out there looking for real criminals like rapists and murderers. But as Law Enforcement Against Prohibition points out, cops who track more violent crimes dont meet their arrest quotas, receive no overtime, no promotion, do not pass go, do not collect $200, etc. Unless of course your violent criminal is a drug lord who doesn’t pay off the cop and the cop is there to rob the dealer. But these days asset forfeitures are more often organized contracts, where the money and assets are all cut up prior to the “raid,” by the various agencies involved.
    In the case of Guzman, the wife runs off with the money, the Federales get the house and the DEA gets the 40 trucks and cars. No bloodshed. Not a shot fired. Because until the C.S.Act is repealed in its entirety, our DOJ, our government agents are the drug cartels. And the only stereotype for that is “traitor.”

  20. Julian, no, good judges are not being “silenced”. They must be too well trained to open their mouths because no one can actually stop a judge.

  21. Unfortunately, I cannot say about Texas. I’ve only lived here a short time. I can tell you more about another state that is unrelated to Texas and not a boarder state.

    I have never been around the DEA. I do strongly believe the agency should not eggsist along with the ATF and CIA. It is completely obvious of the corruption in system, or should I say corporate system. But I can’t give you much information other what other say like yourself as an example.

    I didn’t want to say this but I do have, let’s say, experience, in the drug “detection” dog area. When I say a lot I mean a lot. I’m afraid if I say more, it will start a verbal bashing compain and I will not be taken seriously. It’s not like I haven’t been verbally bashed before but, I just rather not this time.

    Thank for the information Julian,


  22. Huh, my last comment says “Julian says”. I apologize for that Julian. I guess my brain was a little gassy (brain fart). It is suppose to say ” Dustin says”

    Sorry for any confusion,


  23. Just remember the officer is not going to say ” The dog alerted on marijuana.” The officer going to say ” The dog is trained to alert on the presence of the odor of narcotics.” After that the DA might ask the officer what narcotic “odors” has the dog been trained in.

    Now there is also the case of “residual odor” they might use. This is total bumpkin as far as I’m concerned (my opinion of course).

    This is the situation were the dog alerts on an object that possible “was in contact” with the drugs. An example would be money. But, what they don’t tell you is about 90% of all money is contaminated. If the dog alerts on your money. Ask the officer to pull a one dollar bill or twenty dollar bill out of his/her pocket and see if the dog alerts on that. I bet they they won’t because they know most money is contaminated. Even the money little old grandma an grandpa have.

    In most case the officer will seize your money because the dog alerted on it. Hopefully, with this knowledge you could possibly save yourself from getting your money seized by reminding the officer of these facts.

    If they do sieze your money just make sure you reminded them of this fact. Note the time and to write it down as soon as you can so that you have it documented.


  24. Julian, I get what you’re saying, but I disagree that about words “becoming bad” for usage because some random sociopaths used those words in the past. It is freaking ignorant to effectively give these losers pieces of our language. Jessie Jackson and his rainbow coalition are just wrong about banning the word.

    I actually know people that are police. Some were stoners before they became officers. Slowly but surely they all turned into assholes and lost all their friends. They would complain about how “No one respects the police anymore” and I’d explain that it isn’t the police’s job to be assholes, pulling someone over for speeding and give them four or five tickets is abuse, that the police didn’t used to act this way… Now they feed off of people stepping over lines drawn in sand and don’t get in trouble if they shoot you for no reason. The fastest way to only have dicks for friends or no friends? Become a cop. I respect the job police do, but police in this country literally 50% garbage officers; their training is wack and they don’t police well and their “blue wall” keeps them from not being pigs.

  25. Julian, I just watched the nigger police of Albuquerque murder someone for no reason. What is happening to this country??? Let me guess, those pigs did everything by the book and they aren’t magically guilt of murder, right?

  26. @Dave,
    Im sorry to hear that you live in New Mexico. Absolutely beautiful, but it’s absolute anarchy over there. It’s so corrupt in New Mexico you may as well call up the Governor to deputize you, put a star on your coat and call yerself Wyatt Earp, cuz there aint no real justice that I could find. From the trailer parks in the desert to the paid security in Angel Fire, there are places no cop in their right mind would go even if they were well trained. Seems to me like legalizing marijuana is one of the few ways we’ll ever reduce the violence in New Mexico. Too bad. Sure is a beautiful state.
    Just keep in mind that “nigger” don’t have the same meaning in every part of the Country. Don’t go to a march in Washington D.C. and get caught saying that out loud. The reaction you might get could take on a whole new meaning for you in life.
    Oh, and about the old “good judge, bad judge” argument; there are laws that prevent judges from speaking about the pending cases of other judges. But there are no laws, at least in our states of New Mexico and Texas, that prevent a judge from soliciting lawyers with pending cases for campaign contributions. In other words, if a crooked government agent, officer, prosecutor or judge want to close a drug case for kickback$ and a good judge isn’t cooperating, they simply SWITCH JUDGES.
    Just save yourself the migrane and donate to Norml.

  27. @Julian says (Dustin),
    Touch your nose!
    Julian says
    Vape a bowl!
    …go to the fridge…
    …you’re oooooout…

    Dustin, there are some serious scandals rising up from all three of those agencies you mentioned. Many of us have heard the tales of how the CIA ran planes with cocaine from Colombia since the 80s to fund private drug wars and sell weapons for profit. But now they’re facing a report that is going to be released any week now about how their torture techniques were useless since 911. And they were busted by their former defender, Senator Feinstein, for cyber attacking her Senate office files.
    As if the DOJ didnt have enough trouble, people are learning more every day about the DEAs SOD program, and the unjust hypocrisy of the Controlled Substances Act that created the agency in the first place. Recent movements from the State Department to deploy state troopers, or DPS to foreign nations under drug war contracts suggest the Obama administration may already be downsizing the role the Department of Justice plays in these, unjust, expensive, ongoing drug wars by switching Departments… Wait, like switching judges! Got us with the ol’ swap and scramble again, didntcha Obama!
    But the one that gets me the most is the ATF. We dont hear much about the Fast and Furious Scandal a few years back when the ATF was busted selling U.S. weapons to both sides of the Mexican drug war… That got a DEA agent killed and thousands of innocent immigrants and innocent Mexican people too.
    But when even less people know is that of a little known law passed in the 80s (backed by the NRA) that allows the ATF to conceal serial tracking numbers of weapons sales in the United States. If you think about what that means, a reporter can’t find out how many bushmaster rifles were sold in the wake of the Newtown massacre… Because the ATF doesnt have to tell them. (Moyers & Company) So they can sell weapons to the Mexican military and warring cartels to contrive a drug war and hide the deal by calling it a “tracer program.” …So they can sell more weapons. This bad law is an integrel component of the military-drug-prison-industrial-complex. (Say THAT hyphenation twice fast).
    Of course, we’re just “conspiracy theorists” if we believe the CIA isnt censoring our “free press” right? But it doesnt help that our free press follow decoy stories with a “look, squirrel!” call. Like when everyone lost focus on Obama’s response to international scrutiny to the failed drug wars at the 2011 Summit of the Americas because the DEA lead the Secret Service to a bunch of prostitutes in Cartagena. So much for the President’s response during an election year. It was a juicy sexpionage story!
    But people are getting their media sources from non for profits, internet sources, and from a rolling event of developing violence that keeps unfolding with “unclear motives…”

    We all wonder if the outcome of gun violence in America would be different if marijuana was legal.

    Im sitting here watching the Fort Hood story, and a reporter says the shooter was on prescribed medication for PTSD. Let me guess; the medication wasn’t reducing symptoms of violence and the prescription wasn’t medical marijuana.

  28. @Steve,

    You are correct about the law enforcement officer possible giving hand signs for the dog to alert. This is only my opinion, but I can testify as an expert on the stand, you can challenge this in court.

    You need to ask if the Officer was involved in the dogs training or if the dog was purchased from a private company. If the Officer was involved in the dogs traning from the beging. If they have been, it isery easly possible they train the dog to alert on objects buy the handler just reaching for the dogs reward, like ball or rolled up towel for example.

    I will give the benifit of the doubt for some officer’s who don’t know they are doing it but I have to believe some officers do it intentionally especially if they are looking for “Probable Cause” especially if they have been called out for the drug team, DEA ect…..

    Some DA’s are getting smarter now asking for more evidence than just an alert from a drug dog now. They want at least two differant things (reasons) for them to even conduct a search.



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