DUI Implied Consent Laws and Refusing DUI Testing

Implied consent laws generally require all motorists lawfully arrested for driving under the influence (DUI) to submit to chemical testing for the purpose of determining blood alcohol concentration (BAC). For drivers, this generally means having to take a blood or breath test, though officers sometimes also use urine testing.

All states have implied consent laws on the books. However, the specifics of these laws vary. In this article, we explain how implied consent laws generally work, some of the state-specific variations, and possible defenses to implied consent violations.

What Is Implied Consent?

The idea behind "implied consent" laws is that all persons who opt to drive on public roadways implicitly agree to take a DUI test if asked to do so by an officer. However, a motorist typically is required to submit to testing only if the requesting officer has probable cause to believe the motorist was driving under the influence.

When Do DUI Implied Consent Laws Make Testing Mandatory?

As noted above, officers typically need probable cause to require DUI testing. In other words, an officer needs to have facts that would lead a reasonable person to believe the suspect was driving or in actual physical control of a vehicle while under the influence of drugs or alcohol.

In many DUI cases, the facts leading to probable cause start with the suspect's driving patterns. For example, swerving, driving unusually slow or fast, and stopping at inappropriate times and in unusual places can supply facts for probable cause.

It's also common for officers to make observations of impairment after making close contact with the driver. For instance, an officer might note the odor of alcohol, slurred speech, or slumped posture—tell-tale signs of intoxication.

Generally, drivers aren't required to participate in field sobriety tests (FSTs). But if a driver agrees and performs poorly, it's fair game in terms of probable cause.

The final assessment, though subject to legal standards, basically comes down to common sense. If a reasonable person in the officer's position would conclude the driver DUI laws, we likely have probable cause.

What Kinds of DUI Testing Do Implied Consent Laws Require?

DUI chemical testing typically involves a blood, breath, or urine test. However, blood and breath tests are most common. In most states, it's the arresting officer who selects which test the driver takes—though a handful of states let drivers choose. Testing usually takes place at the police station or a medical facility after the motorist has been arrested. However, officers are sometimes equipped to conduct a proper breath test at the arrest site.

Which States Have DUI Implied Consent Laws?

All states have implied consent laws. The basics of these laws are generally the same. However, the details of what implied consent laws require of drivers and officers (a few examples were given above) and how implied consent violations are penalized (explained below) differ by state.

What Are the Consequences of Violating Implied Consent Laws?

State penalties for implied consent violations vary. But some common consequences for implied consent violations include license suspension, increased fine amounts and jail time, and restrictions on limited driving privileges during suspension and following license reinstatement. These penalties can be imposed administratively by the DMV or a criminal court.

An unlawful refusal of DUI testing can also hurt a driver's chances of winning at trial.

License Suspension for Refusing DUI Testing in Violation of Implied Consent Laws

Across the board, motorists who refuse DUI testing are looking at license suspension. The suspension period for a refusal is normally longer than it would be for a failed test (in other words, a BAC of .08% or more).

License Restrictions for Refusing a Blood, Breath, or Urine Test in Violation of Implied Consent

Suspensions for chemical test refusal—as opposed to a failed test—might involve additional restrictions like having to install an ignition interlock device (IID) during or after the suspension. Some states also prohibit "hardship licenses" (limited driving privileges) for drivers who refuse testing.

Increased Criminal Penalties for Implied Consent Violations

Drivers who are convicted of driving under the influence face criminal penalties. These penalties often include fines and jail time. In some states, convicted drivers who also refused testing will be looking at more jail time and more expensive fines than would ordinarily be the case.

How DUI Test Refusals Can Affect a Criminal Trial

Prosecutors often use test results to prove a DUI in criminal court. Of course, when a driver refuses to test, the prosecution won't have this evidence. Without chemical test results, it can be difficult for a prosecutor to prove a "per se" DUI charge (which is based on the amount of drugs or alcohol in the driver's system). However, prosecutors are generally allowed to inform the jury of the defendant's refusal. With this information, a jury may be apt to convict even without test results.

Defenses to Implied Consent (Test Refusal) Violations

The defenses to implied consent violations vary depending on state law and whether you're fighting an administrative license suspension (from the DMV) or criminal charges or penalties.

Implied Consent Defenses Based on Warrants

When criminal charges and penalties are at stake, police generally need a warrant to take a driver's blood. If police do a blood draw without a warrant, the driver might have a good defense in criminal court. However, the warrant defense typically won't work for breath tests or when fighting DMV-imposed license suspensions and license-related penalties like IIDs.

Defenses Based on Inadequate Advisement of Rights

Generally, you can't be penalized for a refusal if you weren't first informed of what was at stake. In other words, the officer must tell you a refusal will result in license suspension. Many states have specific advisements that their officers must give before requesting DUI testing. An inadequate advisement can provide a driver with a good defense in DMV and criminal proceedings.