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Can Police Legally Test You for Drugs/Alcohol at a Stop?

If you’re wondering whether or not the police can give you a drug or alcohol test at a traffic stop, the answer is that they can. That’s because of “implied consent laws,” and this means that you give implied consent to be tested for drugs or alcohol when you’re pulled over if the officer has probable cause.

How is Probable Cause Determined?

Probable cause means that a reasonable person would believe that the individual has committed a criminal act, and it’s a higher standard than reasonable suspicion. There are a variety of ways that an officer can determine that it’s more likely than not that an individual was driving under the influence of alcohol or drugs.

If you are displaying behavior that a “reasonable person” would consider potential evidence of drug or alcohol intoxication, this begins to build reasonable suspicion. Then, you may be detained for a field sobriety test, where they can give a swab test, breathalyzer, Field Sobriety Exercises (FSEs), or other tests. Your performance on these tests may give the officer probable cause to arrest you and order a chemical test for drugs or alcohol.

What are Your Rights When It Comes to Drug and/or Alcohol Testing?

While you can refuse the drug or alcohol test, there are consequences for doing so. In some states, you could lose your license for a year and face more serious consequences if you end up being convicted of driving under the influence.

Furthermore, some states have laws that allow police to quickly get a warrant to perform a chemical test for drugs and/or alcohol. Refusal of the test after the warrant is obtained could result in contempt charges.

How is the Test Administered?

These are the most common ways that a drug or alcohol test is performed:

  • The Breathalyzer – Breathalyzers are able to test for alcohol, but they cannot detect other substances.
  • The Mouth Swab Test – Mouth swab tests are able to detect drugs, but they can detect drugs that were no longer affecting you at the time of the traffic stop.
  • Blood Tests – Blood tests are designed to determine current intoxication from drugs, but this test is quite invasive and must be performed by a medical professional.
  • Urine Tests – Urine tests detect drug metabolites in your urine, though they aren’t effective for determining current intoxication.


Drug and alcohol tests can be administered at a traffic stop, but your rights to refuse them vary from one state to another. However, all states have an implied consent law when it comes to drug and alcohol tests.

Author Harper Harmon is a freelance writer and blogger who focuses on business, health and other various topics. She graduated with a bachelor’s degree in communication from UCLA and currently resides in Santa Cruz with her dog, Sassy.


Bob Kraft

I am a Dallas, Texas lawyer who has had the privilege of helping thousands of clients since 1971 in the areas of Personal Injury law and Social Security Disability.

About This Blog

The title of this blog reflects my attitude toward those government agencies and insurance companies that routinely mistreat injured or disabled people. As a Dallas, Texas lawyer, I've spent more than 45 years trying to help those poor folk, and I have been frustrated daily by the actions of the people on the other side of their claims. (Sorry if I offended you...)

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