The  New York Times reports on the police tactic of “surreptitious sampling” of suspect’s DNA in their effort to investigate crimes.  What this means is taking the cigarette butt, the water glass, whatever the suspect once used in a way that would leave a sample of DNA behind, for testing.  The problem is that the suspects leave their DNA behind unwittingly, providing evidence for law enforcement to scoop up and use at will.

Critics argue that by covertly collecting DNA contained in the minute amounts of saliva, sweat and skin that everyone sheds in the course of daily life, police officers are exploiting an unforeseen loophole in the requirement to show “probable cause” that a suspect has committed a crime before conducting a search.

“The law cannot tolerate such back-door methods, which seize something that any reasonable person expects to remain private,” Mr. Gallego’s lawyer, David Lynch, wrote in a motion to suppress the DNA evidence extracted from the cigarette butt.

Normally, cops would be required to get a warrant to obtain a sample of DNA from a suspect.  This “back door” method allows them to circumvent that need, and allows them to do so without a showing of probable cause or alerting the suspect to the nature of their interest.

In its favor, the argument is that the suspect has abandoned the property from which the DNA sample is collected, and therefore has no reasonable expectation of privacy left.  While it might be disingenuous to say that the suspect intentionally abandoned his DNA, it would be accurate to argue that he abandoned his cigarette that happened to contain a sample of his DNA.  Are the cops to blame if the suspect doesn’t put 2 and 2 together?

There are external policy considerations that are implicated in the collection of DNA samples, however, that are quite disturbing:

The privacy implications of surreptitious DNA sampling may extend beyond individual investigations. The police, critics say, could collect DNA deemed “abandoned” from targeted individuals and monitor their movements even if they are not suspected of committing a serious crime. Innocent people whose DNA turns up unexpectedly may find themselves identified by a database file that they did not know existed.

Imagine hearing your name on the evening news as being identified as a person of interest in a horrific crime based on some preliminary DNA testing, because your DNA just happened to be in a law enforcement databased somewhere.  That would be decidedly unpleasant.

This problem, of course, could be addressed by controls over government databases by deleting DNA from suspects who have not been shown to have been involved in any crime.  But few of us trust the government to do so, or do so satisfactorily even if they tried.  The abuse potential is high, and for the innocent party who gets caught up in police interest, there would be no remedy to undo the damage.

But as for using the surreptitious sampling, aside from the potential for abuse, the argument that it violates the constitutional prohibition against unlawful searches is hard to make stick.  As long as police aren’t actively engaged in creating the abandonment scenario, or faking it as has happened as well, it’s hard to understand what privacy interest a suspect maintains in his discarded cigarette butt.  It seems to fit perfectly into the paradigm of abandonment, which makes it fair game for police.

Another approach that has been suggested is to carve out a separate rule to apply to DNA sampling, aside from the reasonable expectation of privacy.

Some legal experts advocate curbs on surreptitious sampling. Albert E. Scherr, a professor at Franklin Pierce Law Center in Concord, N.H., who has a grant from the National Institutes of Health to study the practice, suggests that the police be required to meet the “reasonable suspicion” standard before secretly collecting DNA. “You’re not asking them to let criminals go free,” he said. “You’re just asking them to investigate a little more.”

While this would certainly help to protect the integrity of DNA collection of innocent people, it’s hard to imagine that the courts or legislatures would be inclined to create such a requirement.  Such a Utopian approach would fly in the face of the get-criminals-at-all-costs attitude that the public loves so dearly.  And it would mean more work for judges, and that won’t win any popularity awards.

Perhaps the only good answer to this problem for the time being is for suspects, and their attorneys, to be aware of the risk of surreptitious DNA sampling and take steps to avoid it.  Don’t leave the butt behind.  Don’t drink the water.  Knowing that DNA samples happen, do what’s necessary to not leave behind the evidence that the police desire, and force them instead to obtain an order on probable cause.