A Maryland trial judge recently ruled the prosecution couldn't use fingerprint evidence in a murder trial. Why? Because, she said, fingerprint evidence isn't reliable. Never mind that the defendant's fingerprints were found on the car of the person who was shot. Does this ruling make sense?

Fingerprint evidence has been a reliable crime-fighting tool for more than a century. Police officers, security experts, prosecutors, defense attorneys -- all rely on fingerprint evidence. Indeed, its use and reliability isn't limited to the courtroom. Many parents, for example, have their children fingerprinted so that if they are abducted, law enforcement has a set of prints to use in the investigation.

Fingerprints are also used to keep track of sex offenders. Under the Adam Walsh Act, convicted offenders must register with local officials, and their conviction and image is posted on a national Web site so the public can know where they are. But they don't just register -- they have to submit their fingerprints to the authorities. Communities rely on the authenticity of those fingerprints.

As combat operations continue in Iraq and Afghanistan, coalition forces continue to engage the enemy. As in all wars, some enemy fighters are captured. Often, they are hard to identify, because they refuse to follow the Geneva Conventions by wearing a uniform and identifying themselves once captured. Those elusive terrorists are identified by their fingerprints. The military relies on this evidence. In fact, they stake their lives on it.

Foreign visitors to the United States are required to place their finger on an electronic reader when they arrive. Their print is instantly compared against a database of other prints. The system was put in place after September 11, 2001, to determine whether someone should be allowed into our country. The Department of Homeland Security relies on fingerprint evidence to protect all of us.

In many states, convicted criminals must provide their fingerprints to the government so that, in the future, if they commit another crime, authorities can compare the known prints to the new prints. Authorities do this because many career criminals use multiple aliases. States rely on fingerprint evidence to hold recidivists accountable.

In some of the most secure business, government and military buildings, you must place your fingers and palm into a reader to gain access to sensitive areas. Since, as we all know, no two fingerprints have ever been proven to be the same, there is a high degree of confidence that the person presenting his or her fingerprint to the reader is the person authorized access to the top-secret area. Security experts rely on fingerprint evidence, and for good reason.

It would be a different story if fingerprints were an untested practice. In our criminal justice system, it is right and proper to test the validity of new scientific techniques. The last thing anyone wants is an innocent person detained or convicted based on unreliable scientific methods.

We must keep an open mind when a criminal defense attorney tests the prosecution's attempted use of a new scientific technique in court whose reliability has not been established. Techniques that have been accepted in the relevant scientific community as reliable have been and should be admitted. Unreliable techniques, and quackery, should be excluded.

But defense attorneys, too, have relied on fingerprint evidence for years. They routinely argue that the lack of fingerprints in a case, or the presence of a third parties" fingerprints at the scene of the crime, is valuable -- reliable -- evidence for a jury to consider.

Fingerprints, in short, have a long and dependable history. The science of reading a fingerprint has proven to be reliable to judges in every country, and indeed in every state in the United States. You and I rely on fingerprint evidence everyday to keep us safe. Indeed, the U.S. Supreme Court, in an opinion written in 1969 by Justice William Brennan said fingerprint evidence is a "more reliable and effective crime-solving tool than eyewitness identifications and confessions."

Perhaps the Maryland trial judge forgot to read that case.
Cully Stimson, a former prosecutor and defense attorney, is a senior legal fellow.