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When is chemical testing conducted in a DUI case?

When law enforcement investigates a drunk driving case, chemical testing is only one of the tools that they have to investigate the case. Law enforcement may conduct chemical testing both before and after an arrest. Chemical testing may occur at the side of the road, at the police station or at a hospital. Here’s when chemical testing is conducted in a DUI case:

After field sobriety tests

A chemical test is an invasive procedure. It’s similar to a search by law enforcement. The law aims to protect members of the public from being subjected to unreasonable searches from law enforcement. The police shouldn’t begin to perform a chemical test until they’ve conducted field sobriety tests. The tests should give them an indication of whether there’s sufficient evidence to proceed with a chemical test.

In rare cases, law enforcement may not perform field sobriety tests. If a person has a physical condition that impacts their balance or if the surface they’re on is very uneven, a field sobriety test may be unreliable. However, in the vast majority of cases, the officer decides whether to proceed with chemical testing in a DUI case only after doing field sobriety tests.

At the side of the road

Law enforcement may administer a preliminary chemical test at the side of the road. This test is called a portable breath test or PBT. A PBT is a device that measures the alcohol content in the air that a person breathes. A PBT is a small, portable device that an officer can keep with them in their patrol car. When they investigate a drunk driving offense, they can take out the PBT instrument to perform the test.

Law enforcement conducts this test at the side of the road. Usually, the PBT test comes before they make an arrest. The purpose of the PBT is to determine if there’s probable cause to make an arrest. The PBT test flashes a result that indicates the driver’s bodily alcohol content.

The PBT test that police administer at the side of the road isn’t as reliable as the breathalyzer that they may give you at the police station. A PBT test is more prone to variations in measurement that may make the test inaccurate. The police should rely on their entire investigation when they make the decision of whether or not to arrest someone and take them to the station for additional testing.

A PBT test can measure only alcohol. If the police suspect you of marijuana use or use of another drug, they may not administer a PBT. The chemical testing that the police choose to administer in your case may vary depending on the nature of the investigation.

After you hear your chemical test rights

If the police make an arrest in your case, they must inform you of your chemical test rights. Even though the law presumes that all drivers consent to take a chemical test, the law enforcement officer must still inform you of your chemical test rights. They must warn you that if you refuse to take the test, the State of Illinois may suspend your operator’s license. The law enforcement officer typically does not proceed with a chemical test until after they’ve given you this warning. If they fail to give you the proper warning, the chemical test may not come into evidence against you if your case goes to trial.

At the police station

Most people who are arrested for drunk driving take a breath test. The breath test most often occurs at the police station. Almost every police station is equipped with one or more instruments for formal breath testing. The police have to follow the rules for performing a chemical test. The police typically administer the breath test after they arrest you and drive you to the police station.

At a hospital

In cases where the police don’t administer a breath test, they may conduct a blood test administered by a medical professional. A blood test in a DUI case is typically conducted after a person is under arrest. The police may have you take a blood test if they suspect that you’re under the influence of drugs instead of alcohol. They may also administer a blood test after you refuse to take a breath test. In that case, the police may have to obtain a warrant to draw your blood if you don’t consent to the blood test.

Evaluating the chemical testing in your case

The police may only administer chemical testing in a DUI case at the appropriate time. They should have reasonable grounds to suspect you of DUI before they ever conduct a chemical test. Formal testing should occur only after a formal arrest and after following strict procedures. Your attorney can help you determine if law enforcement conducted chemical testing appropriately in your case.