HARRISBURG — Newly elected Gov. Tom Wolf imposed a moratorium on the death penalty in the state Friday, calling the current system of capital punishment “error prone, expensive and anything but infallible.”

The Democrat said the moratorium will remain in effect at least until he receives a report from a legislative commission that has been studying the topic for about four years.

Wolf announced the policy less than a month after taking office, fulfilling a campaign promise.

Pennsylvania has executed only three people since the U.S. Supreme Court restored the death penalty in 1976. All three had voluntarily given up their appeals.

Law enforcement groups and Republican lawmakers responded with criticism of the move.

The Pennsylvania District Attorneys Association said Wolf had no authority to impose the moratorium and called it a misuse of the concept of a reprieve.

“He has rejected the decisions of juries that wrestled with the facts and the law before unanimously imposing the death penalty, disregarded a long line of decisions made by Pennsylvania and federal judges, ignored the will of the Legislature, and ultimately turned his back on the silenced victims of cold-blooded killers,” the association said.

A legal challenge in response was likely, an association spokesman said.

The president of the Pennsylvania State Troopers Association called the decision a sad day and said the governor’s actions prevent the state from securing the death penalty for Eric Frein if Frein is convicted in last year’s ambush killing of state police Cpl. Bryon Dickson.

But Pike County District Attorney Raymond Tonkin said Wolf’s moratorium isn’t “any legal impediment” to the state’s plans to pursue a conviction and death sentence for Frein in Dickson’s death.

Wolf said he is granting a temporary reprieve to Terrence Williams, scheduled for execution March 4 for killing two men. Williams admitted killing them while in his teens but now says both men had been sexually abusing him.

Pennsylvania’s death row, which has been shrinking, houses 183 men and three women. The most recent execution was Gary Heidnik in 1999, convicted of killing two women he had imprisoned in his Philadelphia home.

The reasons for the state’s lack of executions have long been debated in Pennsylvania legal circles. Some have attributed it to death penalty opposition among judges on the 3rd U.S. Circuit Court of Appeals or to aggressive tactics by lawyers who defend people facing execution.