The Police are Asking for my DNA

What if the police approach you, and ask for a sample of your DNA? What if they ask for a DNA sample (spit, blood, etc.) because the police say that your name came up in an investigation? Should you provide a sample of your DNA because you have nothing to hide? Should you provide a sample because otherwise the police might get suspicious? Can you refuse to provide your DNA when the police ask?

It is quite important that you know your rights when the police ask you to participate or cooperate in an investigation, including when police ask for a sample of your DNA. Unless the police have a warrant, you do not have to provide a sample of your DNA. If the police are requesting a sample of your DNA without a warrant, you should seek immediate legal advice from an experienced criminal lawyer before making any decision to do so. In Canada and the United States, law enforcement is starting to rely more and more on forensic techniques such as DNA analysis to investigate crimes. You might be familiar with the case of Marissa Shen, a teenager from Burnaby, B.C., who was found deceased in Burnaby’s Central Park in July 2017. Police identified and arrested a man believed to be involved in her death by using a technique called “DNA Dragnet” or “DNA Sweep”.

DNA Dragnet involves mass DNA testing where police ask a number of people to provide a sample of their DNA in the hopes of identifying the perpetrator(s). Police might ask you to participate even if you do not have any connection at all to the victim or the crime, as long as you are considered as part of a “class of people” that could have committed the crime. This could mean being in the same neighbourhood or town as the victim or where the crime occurred. It could also depend on whether you belong to a certain ethnic/racial group or nationality. You might be considered part of the “class” if you fit the “profile” of the perpetrator.

It is lawful for police to obtain a sample of your DNA if they have a warrant or if you consent to it. Police usually take saliva swabs, hair samples or blood samples. In many cases, it might be difficult to say no to police who are requesting for a DNA sample. You might feel some pressure to agree because it might seem suspicious if you refuse, or because you know that other people are providing their DNA. Perhaps you are hard-pressed to say no because you simply want to help. The bottom line is that if the police do not have a warrant, you have no legal obligation to provide your DNA to the police and should never provide your DNA without first seeking advice from an experienced criminal lawyer. 1

As mentioned, it is unlawful for police to demand or force you to give a sample without your consent. Even if you do consent, it must be free or voluntary, and it must be clearly communicated by your words or actions. It must also be “informed consent”- this means that you must know or be told of the nature or reason for the DNA request and what it will be used for. It also means that you must be aware or be told that you have the right to refuse to give your sample. The police may ask you to sign a consent form, which you should carefully review and understand before you sign. It is highly recommended that you consult a lawyer before you sign any such forms.

Perhaps more importantly, you must be made aware of the potential consequences of giving a sample of your DNA. This may include eventually being charged for the crime that the police are investigating. While the police may not use your sample for any other purpose or investigation, there is a risk that you may get implicated in another unrelated crime that the police are investigating. This may happen even if you are completely innocent, because it is entirely possible for the people who handle and analyze your DNA to make mistakes. Therefore, it is quite important that you know your rights that you can exercise during a police investigation that includes a request for DNA samples.

If you are being asked to provide a DNA sample or if you have been charged for a crime after providing or refusing to give a sample, it is recommended that you consult an experienced and knowledgeable lawyer who will make sure that your rights are protected. Whether your rights were respected is often an important issue in cases where the police have requested or obtained any bodily samples from you.

For additional information about providing DNA samples to police and your rights during police investigations, give us a call toll-free at 1-833-784-7500 or email us at

Vincenzo Rondinelli, “The DNA Dragnet: A Modern Day Salem Witch Hunt?” 2003 10 CR (6 th ) 16.

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