Most of the time, when someone is accused of impaired driving, it’s because they’ve been drinking alcohol. Police officers can use numerous different tests to determine someone’s blood alcohol concentration (BAC). What they’re looking assessing in doing so is the percentage of alcohol in that individual’s bloodstream. This calculation can be determined through a breath test, a urine test or a blood test.

However, alcohol isn’t the only substance that can impair someone’s ability to drive. It is also illegal to drive under the influence of other substances that could make it more difficult to drive safely. But this is when it gets tricky, because certain types of drug tests may confirm the presence of certain substances in a person’s system for far longer than they would actually have an effect on someone’s ability to safely operate a motor vehicle.

Cocaine lasts for 1 to 2 days

A good example of this phenomenon is cocaine use. If someone uses it and immediately drives, therefore driving while they’re still high, they are impaired and this is a violation of the law. But cocaine use can show up in a blood test for the next 48 hours. If someone used cocaine two days before they got pulled over, they may fail a drug test, even though they wouldn’t still be high while driving the car.

Marijuana lasts for two weeks

Another example is marijuana, one of the most commonly used drugs after alcohol. It can show up in a blood test for two weeks. Someone who smokes marijuana may only be high for a short time, whereas someone who uses edibles could be high for a few hours. But they would certainly be sober two weeks later, despite the fact that they could fail a drug test.

Things only get worse if the police are using urine tests instead of blood tests. In a scenario like that, marijuana use could show up for the next 30 days. Cocaine could show up for the next 3 to 4 days. Urine tests are not as precise because they show drug use for such an extended period of time. This is why they’re often used for drug testing by employers, but they don’t work as well for the police.

As a result of these realities, if you’re ever charged with “drugged driving” due to a positive test, even though you haven’t been high in days or weeks, it’s going to be important to seek legal guidance as soon as possible.