A major expansion of New York State’s DNA database signed into law last week by Gov. Andrew Cuomo will enhance the ability of law enforcement to convict the guilty and, in some cases, exonerate the innocent. But, disappointingly, the measure still leaves New York State without certain protections to avoid wrongful convictions.

The new measure requires people convicted of any crime, including misdemeanors, to submit a DNA sample. It exempts those without a criminal record convicted of possessing small amounts of marijuana.

Violent criminals often commit multiple offenses before getting caught, including minor ones, warranting the broadened collection of DNA samples that can be searched for possible matches with crime-scene samples. Assembly Democrats deserve credit for insisting on provisions, included in the final measure, to make it easier for defendants and convicted persons with claims of actual innocence to obtain testing for DNA evidence on the order of a judge. Those provisions draw on recommendations by a task force on wrongful convictions created by the state’s chief judge, Jonathan Lippman.

Regrettably, other important reforms sought by the Assembly did not make it into the final bill, leaving unaddressed two of the biggest causes of wrongful convictions: witness misidentification and false confessions. The proposed changes would have mandated the videotaping of police interrogations and “double blind” police lineups so neither the witness nor person administrating the lineup knows the identity of the suspect. Mr. Cuomo says he supports both reforms but had to omit them to reach a compromise on the DNA database expansion. Had he pushed for the videotaping and lineup changes early in the process instead of getting behind the database-only bill favored by Senate Republicans he might have been able to achieve more. Mr. Cuomo has said he intends to revisit the overlooked issues. He should do so soon.