The big question in the debate over expanding the state’s DNA database of convicted criminals is why the legislature might not pass a comprehensive bill. The prospect of such a failure has led Governor Pataki to threaten lawmakers with the possibility that he will call a special session, and the governor was dissatisfied with a watered-down compromise proposed by some Democrats yesterday. When we discussed the issue yesterday afternoon with the district attorney of New York County, Robert Morgenthau, he noted that the use of DNA in crime fighting is “the single most important development in law enforcement in the past 50 years.” he question for Albany is whether police and prosecutors will be able to make full use of that development.

New York currently maintains a DNA databank that stores the genetic fingerprints of about 14% of those convicted of crimes in the state, mainly those found guilty of sex-related offenses. The bill Mr. Pataki is pushing would expand that databank to include all convicts. Mr. Morgenthau, whose long prosecutorial experience has taught him a thing or two about criminals, argues that the move makes perfect sense. Rapists and murderers often start their criminal careers with lower-level crimes. One informal survey performed by Mr. Morgenthau’s office found that in seven of the 40 rape cases examined, the rapist had already been nabbed for five or six lesser crimes by the time he committed the rape. Those starter crimes aren’t always violent, which raises questions about the usefulness of the compromise proposal, which would include only violent offenders.

The man convicted in 1998 of the Park Avenue killing, John Royster, was first called in for questioning in the murder of Evelyn Alvarez because a fingerprint found at the scene matched his, which had been collected when he was brought in for turnstile jumping before his crime spree. A rape in Greenwich Village in 2002 went unsolved until the suspect was caught for another crime and DNA-tested in Florida, but it was later discovered that he had three prior misdemeanor convictions in New York.

Given the potential usefulness of an expanded DNA databank, resistance seems a little misplaced, especially since DNA is not conceptually different from fingerprints. Both are unique to individuals and do not change over a person’s lifetime. The main difference is that the law already allows the police to keep records of fingerprints of anyone who is arrested for a crime. So it’s passing strange that some in Albany, as well as civil libertarians, don’t think police should be able to do the same with the DNA of people who are actually convicted.

Opponents of the measure are correct to note that DNA is not infallible, and that human error at the crime scene or in the lab can negate its value. They also object to the cost of maintaining such a databank and worry about overloading labs. Those are reasonable concerns, but misplaced. Even with a databank, guilt would still be a question for a jury, and defendants would have plenty of opportunities to alert jurors to the potential for human error in the process, just as they do today. Meantime, DNA testing grows cheaper every year. Once an expensive procedure performed only by the FBI lab, reliable tests can now be performed for less than $20.

A comprehensive DNA databank would aid the public by making it easier to catch suspected criminals before they had a chance to victimize additional people. It would also shorten costly investigations. It would help the innocent, since DNA has proven to be an important tool for exonerating people who might, in an earlier day, have been convicted merely for being at the wrong place at the wrong time. Mr. Morgenthau suggests that it would be “incredibly shortsighted not to take advantage of this incredibly important tool.” New Yorkers will be watching Albany closely to see which legislators agree.