Can the Police Force Me to Take a Drug Test After an Accident?

The police need a reason—and potentially a warrant—to test for drugs or alcohol in your system after a car accident.

By , J.D. University of San Francisco School of Law
Updated by Stacy Barrett, Attorney UC Law San Francisco
Updated 5/01/2023

You can't drive safely when you're impaired by alcohol, illegal drugs, or medication. In 2020, 11,654 people died in alcohol-impaired traffic accidents according to the National Highway Traffic Safety Administration (NHTSA). It's harder to say how many people are killed each year by drug-impaired drivers, but a study of drivers involved in serious injury and fatal crashes at trauma centers in 2019 found that 56% tested positive for at least one drug.

Impaired driving is a widespread and serious problem, but that doesn't mean the police can force all drivers involved in car accidents to give blood, breath, or urine samples to test for drugs or alcohol. Instead, drivers typically must submit to testing only if the requesting officer has probable cause to believe the driver was driving under the influence.

What Is an Officer's Role at a Car Accident Scene?

Police typically respond to car accidents that involve injuries or significant property damage. Law enforcement agencies simply don't have enough resources to respond to every fender bender.

When officers respond to a car accident scene, their main priority is safety. An officer's role at an accident scene includes:

  • requesting emergency medical services for anyone who's injured
  • securing the scene
  • redirecting traffic
  • clearing up accident debris
  • interviewing car accident witnesses, and
  • gathering evidence (photographs, measurements, physical evidence.

You'll notice that routine drug and alcohol testing of drivers involving in the accident isn't on this list. But, as is the case during a routine traffic stop, if an officer has reasonable suspicion to believe a driver involved in an accident is drunk or on drugs, the officer can start a DUI investigation and may ask the driver to complete field sobriety tests (FSTs).

When Is a DUI Blood or Breath Test Required?

Crashing a car alone isn't enough to justify an officer launching a full DUI investigation. But if an officer notices a driver showing signs and symptoms of intoxication after an accident—slurred speech, unsteady gait, an odor of alcohol or marijuana—the driver will be detained for further investigation.

If you're detained for a suspected DUI, the officer will likely ask you general questions like, "Where are you coming from?" and "Have you had anything to drink or taken any illegal drugs or medication tonight?" If the officer suspects you're intoxicated based on your answers and the officer's observations, the officer will ask you to perform a few field sobriety tests.

Field Sobriety Testing

Field sobriety tests (FSTs) are exercises designed to test your level of impairment. The three most commonly given FSTs are the walk-and-turn, the one-leg stand, and the horizontal gaze nystagmus (HGN) test (sometimes called the "follow-the-pen" test).

Your performance on the FSTs can give the officer probable cause to arrest you for a DUI. You don't have to perform the FSTs, but declining to do so doesn't mean you automatically get to go home. In most cases, if you say no to the FSTs, the officer will ask you to take a blood or breath test.

Pre-Arrest Preliminary Breath Test (PAS)

When an officer suspects you've been driving under the alcohol, the officer will ask you to take a preliminary breath test (PAS) in addition to the standard FSTs. You can refuse to take this preliminary test without consequences. But if you refuse to take a DUI chemical test after you've been arrested for driving under the influence, you'll face consequences under your state's implied consent laws.

Post-Arrest Evidentiary Chemical Tests

Every state has some form of "implied consent" law that requires drivers arrested for DUI to take a blood, breath, or urine test (called "chemical tests"). The police use these chemical tests to test for the presence of alcohol and drugs in a driver's system. Drivers who refuse to test after a lawful DUI arrest face penalties.

Penalties for Refusing to Test

Implied consent laws vary from state to state. In most states, the penalties for refusing to test include, at a minimum, a license suspension ranging from 90 to 180 days. The Foundation for Advancing Alcohol Responsibility ( has a map of implied consent laws with a summary of penalties in each state

Some drivers are willing to accept the penalties for refusing to test under the mistaken belief that they can't be prosecuted for a DUI without chemical test results. But most states allow prosecutors to introduce evidence of a driver's refusal to test and argue that the refusal is evidence of the driver's "consciousness of guilt."

Moreover, all states have two types of DUI laws—impairment and per se laws. "Per se" DUI charges are based on drivers having a certain amount of drugs or alcohol in their systems. Impairment charges are based on actual impairment and don't require chemical test results—an officer's observations and a driver's performance on the FSTs are evidence enough to prove an impairment charge.

The administrative penalties for refusing to test are stacked on top of criminal penalties for driving under the influence.

Talk to a Lawyer

If you've been arrested for a DUI, talk to a lawyer as soon as possible. An experienced DUI lawyer can help you understand your legal rights and get you the best possible outcome in your case.

A DUI involving a crash is often more complicated than a typical DUI. Learn more about when to lawyer up after a car accident. When you're ready, you can connect with a lawyer directly from this page for free.

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