How Confirmation Bias Affects Police During a DUI Investigation:

Explaining Confirmation Bias to Juries:

Recently, there has been many discussions as to whether police officers invent facts or potentially even lie in court. I do not believe those police officers are fundamentally dishonest. In fact, I believe that the vast majority of police officers are honest people trying to do an incredibly difficult job. I will also say, this is a job that very few people would ever want. The pay is severely inadequate, the hours are long, and police officers deal with some of the most difficult situations and people in the world.  I am sure that at the end of their shift there is nothing worse than cleaning the vomit off of their back seat, from a person just arrested.  

That being said, many police officers exaggerate evidence and sometimes see things that are not there.  Why? The answer is simple: they are human beings. Economists discuss something called, confirmation bias. My position is that most police officers suffer from this same confirmation bias.

Confirmation Bias Defined:

Confirmation bias is the tendency to notice and give more attention to the things that validate one's beliefs and to ignore or undervalue the things that contradict one's beliefs.  I believe police officers suffer from confirmation bias during DUI investigations. 

Essentially, confirmation bias tends to favor an opinion or a viewpoint that confirms what a person already believes or suspects. Confirmation bias affects police work especially as it relates to DUI arrests. When a police officer believes that someone is potentially guilty of a crime, he or she will tend to then look for facts to confirm his or her beliefs. This is because they are human beings, not because they are bad people. It is the same reason why somebody will watch a single news channel and then has their beliefs confirmed by the news channel that already matches his or her viewpoint. This is what confirmation bias is all about. 

The problem of confirmation bias is one of the reasons why in medicine there are controlled studies. Those conducting a study will attempt to control for environmental factors or geographical locations that can affect the outcome of the study.  For example, when scientists test the efficacy of a heart medication, they control for a person's age, geographic location, diet, environment, and possibly even socioeconomic factors.  The reason is that those factors can change the result of the study as to whether the medication works or not. 

Can the Police “Control” for Their Biases?

When a person is being arrested, there are no controlled studies when it comes to a police officer making a judgment as to whether someone has committed a crime. The officer comes into every situation with their biases.  Then they factor in what they believe as an indication of whether someone is driving under the influence, even if those beliefs are outside of what should be considered under the law. 

The police are taught to make assumptions related to the time of day, the make and model of a person's car, the speed of the driving, the manner of the driving, whether the person is older or younger, and whether they have passengers.  When a person makes an assumption during an initial interaction with someone else, he or she subjects themselves to potential confirmation bias.  

Additionally, when a police officer asks a person from where they are coming, this can add to the problem.  For example, telling a police officer that you are coming from a bar or restaurant late at night creates in the officer an assumption of drinking.  As discussed, assumptions are the genesis of most confirmation bias. 

After the officer has made his initial determination based on factors outside the law, the officer then asks the driver to complete a series of field sobriety testing to determine if they are under the influence of alcohol or drugs. These tests are 100% subjective, yet, they are being interpreted by the same police officer who already has a potential bias against the driver. These biases are not personal and do not mean the officer is dishonest.  However, it does not negate that these biases still exist. The officer is simply conducting these field tests to confirm what they already believe. Not surprisingly, the person is then subsequently arrested for DUI. 

Even worse, the officer many times will conduct what is called a preliminary breath test before he or she conducts his roadside field sobriety evaluations. This breath test is not admissible in court due to its known inaccuracy. Still, it provides the officer with a numerical reading which then causes the officer to form a belief about the person with whom they are investigating for a potential DUI.  As a result, the officer's scoring of the field sobriety tests is tainted by the fact they have already seen a result on a breath test, even though they are aware the Alco-Sensor results is known to be inaccurate. 

My point is that I do not believe that police officers make up evidence. Of course, there are always instances of an occasional bad apple, but instances of bad police officers are no different from when we have bad doctors, bad lawyers, and bad people in any other profession or walk of life. 

That being said, assuming police officers are good people trying to do their job, it is clearly obvious that their biases are not controlled for when they are interpreting the performance of individuals they are accusing of drunk driving.  When you add in that a person often admits to the consumption of some alcohol before driving, how can we expect more of police officers?

Practice Example: 

My point can be seen in the following example: Last year I represented a woman charged with a DUI in DeKalb County. The moment she was pulled over the officer assumed she was driving under the influence. He did so because he made assumptions about her because her circumstances were typical of a person who may be DUI.

The officer stopped her vehicle at almost 4:00 AM on a Saturday morning.  She was wearing an evening dress. She was extremely exhausted and being tired affected her driving.  Her fatigue certainly had an impact on her performance on field sobriety testing and even her ability to answer questions coherently.  

Even worse, she had a restricted license because of a previous DUI arrest.  His awareness of the DUI sounded an alarm in his head that could not be turned off.

The officer did not believe her when she tried to explain from where she was coming, and he immediately started interrogating her. She was nervous and did not do a good job of answering his questions. He accused her of not telling the truth.  This caused her even more anxiety.

Ultimately, the officer suspected she was under the influence. She performed field sobriety testing. It was a good thing there was a video because the officer's scoring on the field sobriety testing exaggerated how poorly she performed because of confirmation bias. 

Now was this police officer in DeKalb County dishonest? No, in fact, I believe he is an honest person trying to do his job. I also like him personally and have known him a long time.  However, he suffered from classic confirmation bias. 

Once he was of the opinion she was DUI, his opinion caused him to then psychologically exaggerate not only how she drove, but also how she performed on roadside testing. However, because there was a video, the jury could see past his confirmation bias and after a presentation in court, she was found not guilty. 

The truth was, she had just finished a two-hour drive from work to her home and she was tired, not DUI. Again, I happen to like this police officer, who will remain nameless. However, he misjudged my client.  Thankfully because she exercised her right to a jury trial, and she was found not guilty. 

The point I am trying to make is that it would be ideal for police officers to be trained to avoid assumptions of guilt based on common traits observed in people who are truly guilty. They should be trained to view individuals and situations as a blank slate.

Why I Explain Confirmation Bias to a Jury:

When I conduct a Jury Trial, much of my presentation is explaining how a police officer can honestly believe a person is guilty of a DUI yet be wrong.  The jury system is the ultimate equalizer.  A panel of impartial and intelligent people, who do not have an interest in the outcome of the case, can make these decisions. This is the beauty of our jury system, and I thank God for it every day!