A Maryland law that requires collection of DNA from individuals charged with a violent crime or an attempt to commit one went into effect at the start of the new year, and that's a good thing. A growing database of DNA evidence has already led to delayed justice for a number of state residents convicted of crimes they did not commit and to the imprisonment of criminals who might otherwise have walked free.
The value of DNA evidence has become increasingly apparent in recent years as it has helped free inmates from death rows across the nation and led to broader questions about the quality of evidence in capital murder trials. Maryland joins about a dozen other states, including Virginia, that allow genetic material to be collected from people before conviction. Along with violent crimes, the Maryland law will affect people charged with first-, second- or third-degree burglary. Gov. Martin O'Malley said the expanded collection was justified in a place where too much violent crime occurs.
Mr. O'Malley and Attorney General Douglas F. Gansler wanted law enforcement agencies to keep DNA samples even if suspects were exonerated. That sparked protests from the NAACP and members of the Maryland Legislative Black Caucus who feared that the law would unfairly target minorities. The legislation was amended to add an automatic expunging process for people found not guilty.
As valuable as DNA can be, as with any criminal evidence, extraordinary care will be needed to ensure that samples are not contaminated by the laboratories charged with processing them. Last August, the director of the Baltimore crime lab was fired after it was revealed that lab employees had not entered their own DNA into a database. That oversight led analysts to identify DNA from lab employees as foreign DNA that could have come from unknown perpetrators. Despite a subsequent positive review of operations at the city lab by the Society of Crime Laboratory Directors, the Innocence Project, which protects the rights of criminal suspects, recently asked the Maryland State Police to investigate the lab's management.
The shadow cast by that DNA problem should be useful as a warning to everyone charged with managing Maryland's expanding DNA collection of the high level of care needed when science is used to serve the interests of justice.