If the police pull someone over and believe they are under the influence of alcohol, they may administer a breath test. This can measure the person’s blood alcohol concentration (BAC) in real time. If they are over the legal limit of 0.08%, the police can then assume that they are impaired.

But it is also illegal to drive while under the influence of other drugs. This includes prescription drugs, especially those that warn that a patient should not use heavy machinery after taking them. How long are these substances going to show up on a drug test?

Many drugs last for longer than a high

Many drugs stay in a person’s system for much longer than the impairment or the “high” caused by using those drugs. For example, say that a driver takes a urine test. This could show evidence of heroin or cocaine use for up to three days. And urine tests are not the only type of tests that are used. For example, drug use can show up in some hair tests for three months. This is much different than measuring the alcohol content in someone’s bloodstream at the moment of their alleged impairment.

Why this matters for arrest scenarios

Police officers cannot accurately assess someone’s impairment level caused by drugs just based on a test for the presence of substances in someone’s body. They may believe that someone has been using opioids, for example, but a test may only show if that person used the substance in the last week. The effects of that drug will likely only last for a few hours and the “high” would have ended days before. Was that driver actually under the influence when they were driving? It’s not possible to say from test results alone, which can affect a defendant’s criminal case.

What defense options do you have?

If you have been arrested on drunk driving charges or because of impairment from another substance, it’s very important to consider how evidence is gathered and what legal options you have. The results of a criminal case can have a massive impact on your future and you need to know what steps to take to better ensure that your rights are protected as you move forward.