NMA E-Newsletter #166 – DNA Sampling at Traffic Stops: Ways to Protect Your Privacy


In a recent E-newsletter (#163, DNA Sampling for Motorists: The Latest Threat to Privacy) we reviewed the case of People v. Thomas in which a motorist was subjected to DNA testing without his knowledge or consent. The court denied his motion to suppress the DNA evidence, and he was subsequently convicted in connection with a string of burglaries.

Motorists in other states have been targeted for DNA sampling as well, typically by swabbing the mouth for saliva. But DNA can also be attained from other bodily fluids, hair, fingernails and flakes of skin. If the practice becomes more widespread, motorists will need to be knowledgeable and assertive in order to protect their privacy rights. We asked a colleague from a civil liberties group as well as a member who is an attorney to provide some guidance on what to do if you’re asked to give a DNA sample during a traffic stop.

The requirements for DNA sampling during a traffic stop are greater than those for conducting a search of your vehicle. Provided you have not given your permission for your DNA to be taken, the police must show probable cause and have a warrant to do so.

If you are stopped for a routine traffic violation you are under no obligation to surrender a DNA sample. If asked, state your objection to the intrusion (be civil but firm) and refuse to comply. By doing so, you have asserted your right to privacy. No reason must be given, but you could further assert your rights by saying something like, “I do not want to give you a sample because I want to protect my right to privacy.”

Circumstances dictate when police can legally sample your DNA without your knowledge or consent. If you discard a cigarette butt with saliva on it, you have abandoned your DNA; the police may take it without violating the Fourth Amendment. On the other hand, if police surreptitiously obtain a DNA sample, which you would not have provided otherwise, this would constitute a violation of the Fourth Amendment.

You can protect your privacy rights during a traffic stop by making sure to retrieve or clean any items containing your DNA. The ruling in Thomas was based on the idea that the defendant abandoned his saliva (which contained his DNA). The defendant might have prevented police from obtaining his DNA sample either by requesting that the breathalyzer tube be returned to him or by having it wiped clean.

Realize you may not be able to retrieve or eradicate all of your DNA. However, it’s important to make the effort in order to demonstrate your intention to control your DNA. This may prevent police from justifying a search on the grounds that you abandoned it. Whether it’s enough to block a search will ultimately be decided by the courts.

There are certain situations, however, in which providing a sample may be unavoidable. If you are stopped on suspicion of DUI, your state’s implied consent law may require you to submit to a blood alcohol test or possibly face a license suspension. (Learn more about how to protect your rights during a DUI stop or at a roadblock.)

If you are arrested and taken into custody, police may be authorized under state law to take a DNA sample. About half the states and the federal government have laws allowing DNA collection from individuals upon arrest for certain offenses. Some states collect DNA for all felony arrests while others only do so for those arrested for serious or violent crimes. In states where a DUI arrest and/or conviction are misdemeanors, the taking of a DNA sample may not be justified under current law. Note that many of these DNA laws are controversial and will likely face court challenges.

You may want to brush up on some general ways to protect yourself at traffic stops. Check out these NMA Blog postings for some helpful tips:How To Handle Yourself During A Traffic Stop and A Practical Guide For Dealing With Traffic Stops.

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