Since Maryland began collecting DNA samples from suspects arrested in violent crimes and burglaries, it has used that evidence to win 58 convictions, including eight in rape cases. As the state's DNA database becomes more extensive and more genetic samples are collected in crime scenes, the usefulness of this tool to solve crimes and put dangerous people behind bars will only grow. DNA evidence is much more accurate than eyewitness identification and more ubiquitous than fingerprints. It may not be so easy as it looks on "CSI" and other TV crime dramas, but its extensive use by law enforcement greatly furthers society's interest in making sure that crimes don't go unsolved.

But a decision this week by the Maryland Court of Appeals threatens that progress by declaring its application in most circumstances to be a violation of suspects' right to protection from unwarranted searches and seizures under the Fourth Amendment. While the court's concern about the constitutional implications of a new development in law enforcement is warranted — indeed, other courts have come to a variety of conclusions on the matter — its reasoning is flawed. Attorney GeneralDouglas F. Ganslershould pursue an appeal to theU.S. Supreme Court.

The case at hand deals with an Eastern Shore man, Alonzo Jay King Jr. When law enforcement officials analyzed a DNA sample taken from him after his 2009 arrest on assault charges (but before he was convicted of that crime), they found a match to a sample taken in an unsolved 2003 rape case. Based on that evidence, Mr. King was convicted of the rape, but he appealed, claiming that the DNA sample was taken unlawfully.

Maryland's Court of Appeals has previously upheld such use of DNA samples taken from defendants after they were convicted, but samples collected as part of the routine booking procedure after an arrest was a new issue. In analyzing the case, the court, properly, sought to balance the defendant's expectation of privacy against the state's interest in conducting a search, but it made a number of miscalculations along the way.

For starters, the majority opinion conflates the presumption of innocence afforded to a defendant prior to conviction with his expectation of privacy. Judges Mary Ellen Barbera and Alan M. Wilner correctly note in their dissent that arrestees' expectations of privacy are diminished in far more intrusive ways than the collection of DNA by means of a cotton swab rubbed for a few seconds inside their cheeks. They are subject to thorough searches of their bodies and possessions (including strip searches, an intrusion the Supreme Court recently blessed), and are observed in states of undress by police and fellow detainees while in jail. They are not even given privacy to use the bathroom. Even the process of fingerprinting could be considered more intrusive, in that it involves covering an arrestee's fingertips with ink.

The majority opinion also fails to recognize how the state uses the DNA samples and the privacy protections built into the law. Rather than loading a suspect's entire genetic code into a database (and with it information that could theoretically provide private details outside of the state's interest, such as a person's propensity for a given disease), a sample is reduced to 13 data points that are unique to individuals but reveal no known physical characteristics. Release of any other information contained in a genetic sample is a crime, and there is no indication that Mr. King's sample or any other was used for purposes besides those authorized in the law.

Finally, the majority takes an overly restrictive view of the state's interest in collecting DNA samples. The court notes that in Mr. King's case (and, presumably in most other instances), the state has other means to determine that a suspect is or is not who he says he is. Fingerprints, photographs and identity documents, the court claims, are more than sufficient to satisfy the state's interest. But other courts have recognized that a suspect's identity is more than his name, address and date of birth but also includes what that person has done. That is to say, the state's interest in Mr. King's possible connection to a 2003 rape is just as strong (and arguably much stronger) than knowing his true name.

The crux of the matter is this: Those charged with crimes have, for decades, been fingerprinted as a matter of routine, and those fingerprints are checked against evidence both in the crime at hand and in unsolved crimes. The use of DNA is more powerful and more technologically advanced, but it is fundamentally the same thing. We hope the Supreme Court will be given the chance to recognize that fact and uphold Mr. King's conviction — and the law that made it possible.