Understanding the DUI Police Report

If you're facing a DUI/DWI charge, the police report is the most important piece of evidence in your case.

By , Attorney · University of Santa Clara Law School

When a person is arrested for driving under the influence (or any other crime), law enforcement writes a police report. The police report basically outlines the reasons for your arrest and the evidence the government will try to use against you in court.

Below, we go into the specifics of what you will typically find in a DUI police report and why it's important for defending against a DUI charge.

What's in a DUI Police Report?

The contents of a DUI police report, of course, depend to some extent on the facts of the case. After all, the circumstances of every case are different. However, here are some of the things you're likely to see in a DUI police report.

Reasons Police Pulled You Over

In order for any traffic stop to be lawful, police must first have reasonable suspicion to believe the driver or someone in the vehicle has broken the law. In other words, police can't just stop vehicles at random without justification.

Police know they must have a valid reason to stop a vehicle. So police reports almost always have an explanation for why they made the traffic stop. For example, the police report might explain that the driver was swerving (indicating possible intoxication), was exceeding the speed limit, or broke some other traffic law.

If the police report doesn't provide an adequate justification for the stop, the defense might have a good argument that the whole case should be thrown out.

Probable Cause for the DUI Arrest

Assuming the initial traffic stop was justified, police next need to establish that the DUI arrest was lawful. For a DUI arrest to be lawful, there needs to be probable cause to believe the motorist was driving while under the influence of drugs or alcohol. In other words, police need to explain why they concluded the driver was in violation of the state's DUI laws.

Although every case is different, here are some of the most common items you'll find in police reports to support probable cause for a DUI arrest.

Driver's Field Sobriety Test Performance

When conducting a DUI investigation, officers typically request that the driver perform one or more field sobriety tests (FSTs). Generally, drivers aren't required to participate in FSTs. However, when a driver agrees to complete FSTs, the officer will normally include the results in the police report.

Most judges consider poor FST performance to be fairly convincing evidence of driver impairment.

Breath Test Results—PAS Tests

Prior to making a DUI arrest, the officer will often ask the driver to take a breath test (blow into a breathalyzer). Pre-arrest breath tests are frequently called "preliminary alcohol screening" or "PAS" tests. Pre-arrest breath tests are normally optional. But, again, when a driver agrees to take a PAS test, the officer will typically include the results in the police report.

Although PAS test results are sometimes less reliable than breath tests performed post-arrest at a police station or hospital, judges are usually willing to consider PAS results in deciding whether police had probable cause to make a DUI arrest.

Officer Observations During the DUI Investigation

In pretty much all DUI cases, the arresting officer makes observations that lead him or her to believe the motorist was driving while under the influence. These observations are normally included in the police report. For example, an officer might explain the driver had bloodshot eyes, smelled of alcohol, and had slurred speech.

Judges frequently rely on officer observations in considering whether there was probable cause to support a DUI arrest.

Prosecution's Evidence Supporting a DUI Charge

Much of what has already been discussed can give you some idea of how the prosecution would try to prove the DUI charge in court.

Indications of Officer Testimony in a DUI Trial

Generally, the police report itself won't be admitted into evidence at a DUI trial. However, based on the police report, you can get the gist of what the arresting officer might testify to in court. For example, the officer would likely testify as to poor FST performance and any observations (such as slurred speech) that would lead one to believe the driver was impaired.

Breath, Blood, or Urine Test Results

Depending on the type of machine police use, PAS test results aren't always reliable enough to be admitted as evidence in court. However, all states have "implied consent" laws that require drivers to submit to post-arrest testing when requested to do so by an officer.

In most cases, post-arrest testing will be of the blood, breath, or urine. (When police do a post-arrest breath test, they use a machine (generally, called an "evidentiary breath test" device) that's more reliable than a PAS device.) The results of post-arrest testing usually are reliable enough to be admitted in court.

Police reports might or might not include post-arrest test results. Breath test results are available immediately and typically will be included in the report. However, blood and urine test samples must be sent to a lab for analysis and sometimes aren't available when police write their reports.

Why Are DUI Police Reports Important to the Defense?

A DUI police report essentially lays out:

  • how the police justified the actions with respect to the traffic stop and DUI arrest, and
  • how the prosecution will likely try to prove the DUI charges at trial.

These two pieces of information are invaluable for defense attorneys in determining whether there are any viable defenses and the likelihood of beating the case.

Pretrial Motions to Dismiss

In many DUI cases, a defense attorney can identify problems with the traffic stop and/or the DUI arrest by looking at the police report. If the stop or arrest was unlawful, the defense can file a pretrial motion to suppress evidence. A successful motion to suppress will often result in the prosecution having to dismiss the DUI charges.

Occasionally, the police report might reveal other problems with the prosecution's case such as there being too much delay between when the offense allegedly occurred and when the prosecution filed the charges. These kinds of circumstances can also give the defense a good basis to move for the dismissal of the charges.

Every case is different. But defense attorneys know what to look for, and the DUI police report often provides at least some information about what kinds of pretrial motions have a chance of success.

Identifying Holes in the Prosecution's Case

For defense attorneys, it's important to identify any areas where the prosecution's evidence might be thin. With this knowledge, a defense attorney can assess the likelihood of beating the charges at trial, including what kinds of defenses might be viable.

For example, if an officer states in a police report that he or she found the motorist stationary in a parking lot, there might be a good defense based on there being inadequate evidence that the motorist was driving or in actual physical control of a vehicle.

Good defenses are, of course, useful at trial. But identifying a viable defense can also give defense attorneys some leverage for plea bargaining.

Get an Experienced DUI Lawyer to Review the Police Report

This article covers the basics of what to look for in a DUI police report. But it's no substitute for the assistance of a qualified DUI attorney. An experienced DUI lawyer can read a police report and get a good idea of possible defenses and how best to handle your case.

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