Fingerprinting is a valuable forensic tool for verifying the identity of a criminal defendant. DNA can provide a more accurate way to establish whether a person was physically present at a crime scene and is being utilized as evidence in a growing number of cases. However, the practice in several states, including Maryland, of swabbing arrestees for DNA has raised constitutional questions regarding the definition of reasonable searches.
- A recent Supreme Court ruling gave Maryland law enforcement the green light to take DNA swabs in addition to recording fingerprints and taking photos as part of the standard booking procedure. A majority of five justices argued that collecting DNA is reasonable when there is probable cause that a serious offense has been committed.
- The dissenting opinion was uncomfortable with the vague definition of “serious offense” and worried that law enforcement agencies were using DNA collection as an investigative tool instead of an identification method. For instance, Maryland police connected Alonzo Jay King to an unsolved rape case using DNA they obtained when they arrested him on an unrelated assault charge. Police might expand the number of alleged “probable cause” arrests they make as a way to expand their DNA databases. As Justice Scalia wrote, “As an entirely predictable consequence of today’s decision, your DNA can be taken and entered into a national DNA database if you are ever arrested, rightly or wrongly, and for whatever reason.”
Expanding the national DNA database might lead to more criminal convictions, but it may also increase the number of people who are wrongly accused and convicted of crimes they did not commit. DNA can reveal a great deal of information about a person, but mistakes at the crime scene or forensic lab can ruin the life of an innocent person.