Put Privacy Aside: Is Collecting DNA From Every Arrested Person a Good Idea?

Today the U.S.  Supreme Court hears arguments in Maryland v. King, the Court’s latest foray into  DNA testing.  Most reports have focused on the clash between law enforcement’s desire to test every arrested person in order to try to solve old cases, and those who advocate for a strict interpretation of the Fourth Amendment’s protection of privacy.  For example, a report by the excellent Nina Totenberg of National Public Radio discussed the positions of police, who believe taking a sample from every person arrested is a minimal intrusion that can have a big payoff, and the arguments of defense attorneys and civil libertarians, who feel that allowing testing of all arrestees would surrender the basic principles of the Fourth Amendment’s protection against unlawful searches and seizures.

But there’s a question that may be far more important: from a crime fighting point of view,   is it a good idea for police to take and process a DNA sample for everyone who gets arrested?   Of course there will be some cases — such as the King case itself — in which the time-of-arrest sample leads to an arrest for a different, serious crime.  But taking samples from every arrestee may actually hurt our efforts to use DNA most effectively to make ourselves safe.  According to an article in Slate by Brandon Garrett and Erin Murphy, real public safety gains from DNA lie not with taking samples from every jaywalker and burglar and hoping for a hit in a cold case, but instead in taking many more samples from crime scenes.  In other words, we get more hits when we process samples from active crime scenes and match them against our already-large DNA database, instead of fishing for leads among the whole population of more than 12 million people arrested every year.  And all of those additional samples from arrestees crowd out and slow down the processing of samples from real crime scenes and victims, creating backlogs.  In other words, bigger DNA databases is not the answer to crime.

[B]igger is only better if DNA databases grow in the right way: by entering more samples from crime scenes, not samples from arrestees. DNA databases already include 10 million-plus known offender profiles. But a database with every offender in the nation cannot solve a crime if no physical evidence was collected or tested.  And police collect far too few such samples….The police solve more crimes not by taking DNA from suspects who have never been convicted, but by collecting more evidence at crime scenes.  Even worse, taking DNA from a lot of arrestees slows the testing in active criminal investigations….Backlogs created by arrestee DNA sampling means that rape kits and samples from convicted offenders sit in storage or go untested.

The bottom line: even if the Supreme Court says we can take a sample from every person arrested, doesn’t mean we should.

 

An Embrace of Science by Law Enforcement

The main point of my book Failed Evidence is to explain the real reasons that law enforcement resists science, and with that understanding to enable us to break through that resistance in order tohave better police work that reflects the best scientific  knowledge that we have.

So what a relief to find an example of law enforcement embracing science in a big way.

In the November 13 New York Times, “Jane Doe Gets a Back Story” tells how police have been aided by science in some very cold cases.  They have turned to isotope analysis to pinpoint the geographic origin of some unidentified human remains, and scientists have been able to do this with almost uncanny precision.  In other words, the scientists have not been able to identify the corpses, but they have pinned down where they came from, which might then lead to an identification.  The case featured in the article involved the frozen body of a woman found floating in a lake under a highway overpass northeast of Tampa, Florida, forty-one years ago.  The best guess was that the woman was white or Native American, and 17 to 24 years old.  Police got nowhere with this scant information.

Fast forward to this year, when scientists used shavings of tooth enamel and bones to come up with some “startling” findings:

The best evidence suggested that she grew up in Greece and came to the United States less than a year before she was killed. (Tarpon Springs, north of Tampa, has a large Greek-American population.) The research, according to Detective [Darren] “turned the case upside down.” Based on the findings, he provided information for an article that was published Oct. 11 in The National Herald, an international Greek-language newspaper. It was accompanied by the new reconstructed image of the victim and her clothing.

The case is still not closed. The woman’s identity has not been determined, and Detective Norris acknowledges that it is still a long shot. But he is confident that he is on the right track. “The best lead that has ever come in this case came because of the science,” he said…

What’s fascinating to me is the strong embrace of this scientific work by the police.  Because as readers of Failed Evidence know, that is not a given.  So what accounts for that embrace, while science on far more basic and common law enforcement methods like eyewitness testimony, interrogation of suspects, and basic forensics gets rejected?