The dangers of growing DNA databases

President Obama may have given credence to a relatively new but questionable law enforcement practice that the rest of the developed world is starting to shun: taking and retaining DNA samples from individuals arrested for a crime but not convicted. That is, putting innocent people's DNA in criminal databases.

During an interview with the president last month on the television program "America's Most Wanted," host John Walsh enthusiastically supported the expansion of this practice in the United States, saying, "We now have 18 states who are taking DNA upon arrest. England has done it for years. It's no different than fingerprinting or a booking photo." To which President Obama said, "It's the right thing to do."

But many in the human rights community disagree. For example, the European Court of Human Rights unanimously ruled in 2008 that the United Kingdom's policy of keeping arrestees' genetic samples after their release -- the very practice that Walsh (and by implication Obama) endorses -- violates a right respecting private and family life codified by the European Convention on Human Rights. At the time...