Implied Consent and DUI: What Happens If You Refuse a Chemical Test or Field Sobriety Tests?

If you get pulled over for a DUI and the officer asks you to take a blood, breath, urine, or field sobriety test, do you have to? What happens if you refuse?

By , Attorney · George Mason University Law School

After pulling you over, a police officer who believes you were driving under the influence of drugs or alcohol might ask you to perform several tests. These tests help officers determine whether they can charge you with DUI. But they might be able to successfully charge you even if you refuse to take the tests.

Types of DUI Tests

Police officers have a few tests they can give to drivers they suspect of DUI.

Officers typically give field sobriety tests (FSTs) and a preliminary alcohol screening (PAS) before arresting someone for DUI. Drug influence evaluations (DIEs) and evidentiary chemical tests usually happen after a DUI arrest.

Field Sobriety Tests

Generally, police use FSTs to decide whether a driver is under the influence of drugs or alcohol. There are three standardized FSTs that police often administer during DUI investigations. Some studies claim to show these standardized tests are reliable for gauging intoxication. The standardized FSTs are the:

  • horizontal gaze nystagmus test
  • one-leg-stand test, and
  • walk-and-turn test.

Police also might use other FSTs, such as asking drivers to recite the alphabet or count backwards.

As a general rule—and unlike with chemical testing—a driver can refuse FSTs without a legal penalty. However, the prosecution might be able to argue that the driver's refusal to perform FSTs is evidence of the driver's guilt.

Preliminary Alcohol Screenings

A PAS device, also known as a "preliminary breath test" or "PBT," is a portable instrument that a driver blows air into to produce a blood alcohol content (BAC) reading. (People sometimes refer to these devices and evidentiary breath testing instruments as "breathalyzers.")

Generally, police use PAS devices during roadside investigations to establish probable cause to arrest a driver. In other words, one of the typical steps before formally arresting a detained driver is conducting this preliminary screening.

PAS devices aren't as accurate as evidentiary chemical tests (discussed below), so the prosecution usually can't use PAS results in court to prove a driver's level of intoxication.

In general, a driver can refuse a PAS without a penalty. But some states do have penalties for refusing a PAS, including fines and license suspensions. Drivers who are younger than 21 should be aware that they might face significant penalties, including a license suspension, for refusing a PAS even in a state that otherwise doesn't penalize PAS refusal.

Drug Influence Evaluations

In drugged driving cases, the police might use a drug recognition expert (DRE) to perform a DIE.

A DRE is a police officer who takes special classes to become certified to conduct DIEs. A DIE is a 12-step evaluation that includes FSTs, physical examinations, and interviews of the driver.

Drivers generally don't have to perform DIEs, which happen after arrest. Put differently, a DIE's steps normally are voluntary and don't result in penalties if the motorist refuses them.

Evidentiary Chemical Tests

Evidentiary chemical tests examine a driver's blood or breath—or, in a few states, urine—to detect intoxicating substances. Unlike a breath test, which can detect only alcohol, a blood test can detect drugs and alcohol. Evidentiary chemical tests generally are more reliable than a PAS. As the name suggests, officers give these tests after they've arrested someone for DUI so that they have more evidence of the alleged crime.

When a case goes to trial, a prosecutor can use evidentiary chemical test results to prove that the driver was under the influence of alcohol. In drugged driving cases, the prosecution generally will need results from a blood test and a forensic toxicology expert to explain how the drug detected by the test would have affected the driver's ability to drive.

Proving DUI Without Evidentiary Chemical Tests

In some states, an evidentiary chemical test must be given within a particular timeframe—usually within a few hours of the time that the motorist was driving. A test taken outside of that timeframe might not be admissible in court. Also, prosecutors won't have an evidentiary chemical test to use in court if the driver refused to cooperate with testing (more on that below).

However, a judge or jury could still find a driver guilty of a DUI without evidence from a chemical test.

To prove a DUI, the prosecution has to establish either:

The prosecution can show actual impairment through non-chemical-test evidence, such as witnesses' testimony about the driver's behavior and poor driving, the driver's statements to the police about drinking or drug use, and the driver's poor performance on FSTs.

What Are Implied Consent Laws?

Every state has implied consent laws. These laws say that a person who drives a vehicle has agreed to take an evidentiary chemical test by just driving on the road. If a police officer arrests a driver for a DUI, the driver is legally required to take a blood, breath, or urine test. A driver who refuses a test will face serious penalties, such as a license suspension.

Even if a driver refuses an evidentiary chemical test, the police might be able to get a search warrant to force the driver to submit to a blood test. Even though the police obtained a blood test with a warrant, they likely still will be able to charge the driver with refusal.

Implied consent laws vary by state. For instance, in some states, implied consent laws don't apply to operating a vehicle on private property.

Refusing to Take an Evidentiary DUI Test

Drivers who unlawfully refuse to take an evidentiary chemical test face serious consequences—sometimes, consequences that are worse than if they were just found guilty of driving under the influence.

Depending on the circumstances and state law, a refusal can result in a conviction that's additional to the one for DUI. Refusal can lead to:

Additionally, if your DUI case goes to trial, the prosecution often can use your refusal against you—arguing that you knew you were intoxicated and that's why you refused to take the test.

Implied Consent and Refusal Laws in Your State

Implied consent laws and penalties for refusing an evidentiary chemical test vary by state. For a summary of the laws in your state, see below.

Alabama Kentucky North Dakota
Alaska Louisiana Ohio
Arizona Maine Oklahoma
Arkansas Maryland Oregon
California Massachusetts Pennsylvania
Colorado Michigan Rhode Island
Connecticut Minnesota South Carolina
Delaware Mississippi South Dakota
District of Columbia Missouri Tennessee
Florida Montana Texas
Georgia Nebraska Utah
Hawaii Nevada Vermont
Idaho New Hampshire Virginia
Illinois New Jersey Washington
Indiana New Mexico West Virginia
Iowa New York Wisconsin
Kansas North Carolina Wyoming
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