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How do the police test drivers for alcohol?

The police gather evidence during traffic stops several ways if they suspect a driver is drunk. They may ask the driver questions, such as if they were drinking or coming from a bar. Or, they may ask a driver to do field sobriety tests, such as standing on one leg, walking in a straight line, looking at a moving object or putting a finger to their nose. However, collecting evidence against a driver using these methods is often outmatched by chemical sobriety tests.

A chemical sobriety test evaluates the blood alcohol content (BAC) in the body. BAC is the amount of alcohol found in the body at the time of testing. The more someone drinks, the higher their BAC will go.

If given the choice, drivers may have three chemical sobriety test options. Before they pick one, it may help to learn about each of the tests. Here’s what drivers should know:

What is a breath test?

The police may carry small portable devices called breath tests that can quickly evaluate a driver’s BAC with nothing more than a breath of air. A breath test is often the most preferred test since they don’t require drivers to leave their vehicles or drive to another location.

There are many myths about breath tests. For example, people have tried sucking on pennies to pass breath tests. This doesn’t do anything. Furthermore, people may try using mouthwash or breath mints to pass breath tests. These products often contain some alcohol and can increase a BAC reading, which could perpetrate a failed test.

What are urine and blood tests?

Alternatively, drivers may go to another location to do a urine or blood test. These tests use bodily fluids to test a driver’s BAC levels. Out of the three tests, blood tests are often the most accurate.

Any of these tests could fail because of other reasons. A driver who takes prescription medication could have a higher BAC reading than normal. Or, a urine or blood test could be contaminated. Drivers may need to learn about their legal options if they believe they were wrongly accused of drunk driving.