The Police Want Your DNA to Prove You're Innocent. Do You Give it to Them?

I have a friend who once, being recently divorced, lived by himself in a house in a mid-sized western city. One night a terrible crime took place: the house across the street from his was broken into, and the elderly woman who lived there was raped. In the course of the investigation, as a single man living near the woman, he came to the attention of the police. The traumatized victim told the police she was pretty sure he was not the perpetrator, but the police approached my friend and asked him to submit a DNA sample to eliminate him as a suspect. They told him they did not really think he was the perpetrator, but wanted to definitively eliminate him out of investigatory thoroughness and in order to reassure his neighbor.

How would you respond to such a request?

On Tuesday I wrote about how some local U.S. police departments are going wild with the collection of DNA, swabbing juveniles and others not suspected of any crime, let alone convicted of a serious one. These samples are then being stored in local police DNA “shadow databases.” As ProPublica reported, many of the samples being added to these databases are “exculpatory” samples used to exclude people as suspects.

As a privacy advocate, I really would not want to share my DNA with the police. They would likely retain it indefinitely, and possibly share it with other law enforcement agencies. I would henceforth be vulnerable to potential misuses of my DNA (just to pluck one potential scenario: to identify me should I mail an anonymous tip or complaint to a government agency). And, I would be much more likely to be mistakenly identified as a suspect, either through human error or just because every time the police run a criminal’s DNA profile I will now be part of the genetic “lineup.” A California man, for example, was wrongly charged with capital murder after his DNA was matched with samples taken at a crime scene (contaminated by the same paramedics who had treated him earlier in the day). That wouldn’t have happened if his DNA wasn’t in the database.

On the other hand, what my friend confronted was a tough request to refuse. The victim was quite sure my friend was not her attacker—but did seem to have some flicker of doubt. By refusing to submit a DNA sample, my friend may have become (however unjustly) much more suspicious to the police—and to his neighbor the victim, and probably his other neighbors as well, as word spread, and potentially the wider geographical and professional communities in which he lived. At least, that was something he worried about. Most likely some people would understand his decision to stand on principle, but others would not. The increased suspicion surrounding him might also raise the risk that coincidental circumstances or false memories on the part of others would start to accumulate as evidence of his involvement in the crime. Compared to such real and potentially severe social costs, how do we weigh concerns about privacy and the use or abuse of his DNA at some later date?

My friend turned over his DNA to the department. He was excluded as a suspect, and that was the end of it for him, though his DNA records no doubt continue to reside in the hands of law enforcement.

Thinking about how I would handle such a situation, it ocurred to me that there might be a middle ground here: provide a DNA sample on the condition that the police promise not to retain that sample, or use it for any other purposes. Of course, to ensure that such a promise were not an empty one, one would want it in writing—and, to have some teeth, such as monetary damages for violation. The ACLU of Massachusetts once had to file suit to seek enforcement of a promise that exculpatory DNA would be expunged.

Perhaps I might ask the police to sign a contract along the lines of the following:

Contract for Provision of Exculpatory DNA to Police Department

This is a contract between ___________ (hereafter, “Subject”) and _________________ (hereafter “Department”).

Subject understands the Department’s desire to definitively eliminate Subject as a suspect in a crime through the acquisition of a DNA sample, and wishes to cooperate with the police in that aim, but does not want Subject’s DNA retained in police or other government databases for any longer than required for this purpose.

Subject hereby agrees to voluntarily provide a DNA sample to the Department. The Department agrees that, provided and upon establishment that Subject’s DNA does not match that of the suspect in the crime being investigated:

  1. Subject’s DNA sample will not be shared or used for any other purposes;
  2. the physical sample of Subject’s DNA profile will be destroyed immediately, and in no circumstances held any longer than 30 days;
  3. any and all data about Subject’s genetic profile derived from that physical sample will be deleted immediately, and in no circumstances held any longer than 30 days.

In the event that Subject’s DNA samples or genetic data collected in this investigation are used for any other purpose, or are subsequently found to reside in any Department database or storage system, or, having been shared or provided by the Department, within the databases or storage systems of any other party, the Department will pay Subject the sum of five (5) million dollars.

Even if a police department refuses to sign such an agreement, the mere act of offering it shows to the police and the community that a person is willing to cooperate as long as his or her genetic privacy is well-protected.

Of course, far better would be to enact privacy laws with good protections in such situations, but where those don’t exist this might be a potential solution for those who find themselves wanting to help the police while protecting privacy, or feeling any kind of pressure to provide a sample.

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30 days after WHAT?
Convicted person's final appeal?


30 days from the date originally collected. DNA sampling is a grievous assault on the 4th ammendment


Nobody has to prove the are innocent of anything. It's unconstitutional for any police officer, prosecutor or investigator to operate a "guilty until proven innocent" investigation.

There are federal statutes that make blacklisting and harassment federal crimes. The U.S. Supreme Court has also ruled that longterm surveillance or stalking is unconstitutional as well, tracking a citizen 24/7 for long periods of time.


The real danger of judges allowing this type of practice is that it creates a culture of "fishing expeditions" which is the opposite of the letter & spirit of the Fourth Amendment (which has never been amended to mean otherwise).

The Fourth Amendment is "chronological". First a real crime has to occur, then if there is real evidence or oath-sworn witness testimony that creates "probable cause", the official applies (under penalty of perjury) to a magistrate judge to approve a search warrant.

The last part is very important, there is a healthy risk of prison or contempt of court penalty for officers or prosecutors that lie or embellish the truth. This creates a deterrent against fraud and corruption by police and prosecutors.

Swabbing someone as part of an unconstitutional fishing expedition should be totally illegal with penalties for the illegal fishermen.


The root cause of the problem is that the U.S. Supreme Court made a huge blunder that has lasted almost 50 years on search and seizure which reversed the meaning of the Fourth Amendment (without a required constitutional amendment).

In the U.S. Supreme Court case "Terry v. Ohio" during the so-called "War on Drugs" the high court created a genuine slippery slope which rewarded illegal police searches. The dissenting opinion, by Justice Douglas, warned that it was taking a step down the totalitarian path by changing the balance of power between the executive and judicial branches. Many Americans feel that is exactly the path we are traveling down today.


This isn't good enough at all.

All they have to do is say they are accusing you of something due to an anonymous tip, even though they were secretly led to you by your DNA. Everything is done secretly now anyway.

Danny Lampley

$5 million is a lot. I could see $5,000 as a defined general damage amount but would also add language to include recovery for all other actual damages plus all attorney fees and costs of court incurred in the enforcement of the contract.


I would put it at 50 million.


Another alternative would be for the police to hire a neutral lab, decided on by the person under discussion, and provide that lab the sample from the perp. Then the other person could supply his or her dna, have the comparison made, and the sample destroyed without the police gaining access to the sample.

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