Yes — police can take your DNA without your consent in several situations. The clearest examples are after a lawful arrest for a serious offense, under a court-issued search warrant, from items you’ve discarded in a public place, and through partial matches to relatives in consumer genealogy databases. Federal agencies can also collect DNA from non-citizens in immigration custody. The Fourth Amendment treats DNA collection as a search, but courts have carved out enough exceptions that whether police need your permission depends heavily on the circumstances.
After a Lawful Arrest
The broadest exception starts at booking. In Maryland v. King (2013), the Supreme Court held that swabbing the inside of an arrestee’s cheek for DNA is a reasonable search under the Fourth Amendment, comparable to fingerprinting and photographing. The Court pointed to the reduced privacy expectations of people in custody, the minimal physical intrusion of a swab, and the government’s interest in accurate identification.
Most states and the federal government now authorize DNA collection from people arrested for qualifying offenses, which generally means felonies. Federal agencies can collect DNA from anyone arrested, charged, or convicted of a federal crime.
Your profile is then uploaded to the Combined DNA Index System (CODIS), the FBI-run network that lets federal, state, and local labs compare DNA profiles electronically. If your profile matches evidence from an unsolved case, that match becomes an investigative lead. Collection happens during booking, but the profile is not supposed to be loaded into CODIS until a judge has made a probable cause determination on the arrest. That step matters because if the case falls apart — dismissed, dropped, or acquitted — federal law requires the record to come out of the database.
With a Search Warrant
If you’re not under arrest, police can still compel a DNA sample by getting a warrant. Officers present sworn facts to a judge showing probable cause that a crime occurred and that your DNA is connected to it. The warrant has to name you and describe the sample being sought.
Once a judge signs it, you’re required to comply. Refusing a valid warrant can lead to contempt charges, and officers may use reasonable force to collect the sample. That’s very different from a voluntary request, where refusal is your right.
Investigators tend to seek warrants when they have a specific suspect but can’t get DNA another way. The probable cause bar isn’t a formality: a hunch won’t clear it, and a judge has to agree the facts tie you to a specific crime.
From Something You Threw Away
This is where most people are caught off guard. A coffee cup dropped in a public bin, a cigarette butt on the sidewalk, a napkin tossed at a restaurant — police can pick any of these up, extract DNA from the saliva or skin cells left behind, and run it through a database. No warrant. No notice. No consent.
The legal theory is abandonment. Once you voluntarily discard something in a place where you have no reasonable expectation of privacy, courts have said you’ve given up Fourth Amendment protection over it. A federal prosecutors’ guide frames it plainly: when someone leaves biological material on an item in a public place that police later seize, “there is no invasion of privacy and thus no federal constitutional right triggered.”
Investigators use this route when they have a suspect but not enough for a warrant. Rather than tip the person off with a voluntary request, they wait for something to be thrown away and test what’s on it.
The doctrine isn’t fully settled. A growing line of challenges argues that analyzing DNA is a much deeper privacy intrusion than possessing a discarded cup. One federal appeals court has held that DNA testing of a lawfully seized item is a “sufficiently separate invasion of privacy” that qualifies as its own Fourth Amendment search. A petition currently before the Supreme Court asks the justices to resolve the split. If the Court takes the case, the rules on abandoned DNA could shift.
Through a Relative’s Genealogy Profile
You can be identified through a genealogy database even if you have never uploaded your own DNA anywhere. Investigators upload crime-scene DNA to a public genealogy platform and look for partial matches — the signature of a biological relative. From those matches, they build a family tree, narrow by age, sex, and location, and work toward a likely suspect. They usually confirm the theory by collecting that person’s abandoned DNA.
The rules on the platform side are tightening. GEDmatch now requires users to affirmatively opt in before their profiles are visible to law enforcement, and searches are restricted to violent crimes such as murder, manslaughter, aggravated rape, robbery, and aggravated assault.
Most states still don’t require a warrant for these searches. That’s beginning to change. Maryland and Montana enacted laws in 2021 requiring judicial authorization before police can search consumer genealogy databases, and Maryland’s law adds further limits on when and how those searches can happen.
The practical reach is what matters. You may never have used a consumer DNA test, but a distant cousin might have, and that alone can be enough to bring investigators to your door. The technique doesn’t need your consent or your awareness.
In Immigration Custody
If you or someone you know is a non-citizen in federal custody, DNA collection rules are broader. Federal law authorizes DNA collection from non-U.S. persons detained under U.S. authority, and a 2020 Department of Justice rule ended a longstanding exemption that had let the Department of Homeland Security skip collection from immigration detainees. Customs and Border Protection and Immigration and Customs Enforcement can now be directed to collect samples from people in their custody.
The categories are wide: criminal arrestees regardless of citizenship, non-citizens in administrative removal proceedings, people subject to expedited removal or reinstatement of a prior removal order, and those who voluntarily withdraw an application for admission. Samples go to CODIS like any other law enforcement collection. A proposal published in late 2025 would extend biometric collection, including DNA, to individuals associated with immigration benefit requests and would remove earlier age restrictions that had exempted children under 14.
Saying No to a Voluntary Request
If you’re not under arrest and police don’t have a warrant, any request for your DNA is voluntary. You can decline. Officers sometimes phrase these requests in a way that makes refusal feel suspicious — “Would you give us a sample so we can rule you out?” — but the choice is yours.
Your refusal generally can’t be used against you in court as evidence of guilt, on the same principle that protects other constitutional rights. Be realistic about what comes next, though. If investigators already have independent evidence, refusal may push them to seek a warrant. Or they may follow you and collect what you throw away. Saying no doesn’t end the investigation; it changes which tools get used.
Getting Your Profile Removed if You’re Cleared
If your DNA was collected after an arrest and the case didn’t end in a conviction, federal law requires your profile to be expunged from CODIS. The trigger depends on how the case resolved. If a conviction was overturned, the FBI must remove your profile once it receives a certified copy of the final court order. If you were arrested but never convicted — charges dismissed, acquittal, or no charges filed within the applicable time — you’re also entitled to have your record purged.
The process is not automatic, and that’s where people get stuck. For federal arrests, the Attorney General’s office needs a certified copy of the final court order showing how the charges ended. An order isn’t “final” while appeal time is still running, so the clock doesn’t start until all appeal windows close. States must follow similar expungement rules as a condition of participating in the national CODIS system, and the responsible state agency will want the same kind of certified court documentation before deleting a profile. The biological sample itself, typically the original cheek swab, should also be destroyed.
Administrative fees for expungement petitions vary by jurisdiction, from nothing to several hundred dollars. If you believe your profile should have been removed but wasn’t, start with the arresting agency or the state crime lab that processed your sample. These records don’t clean themselves up.