WASHINGTON — Debate over waterboarding flared yesterday on Capitol Hill, with the CIA director raising doubts about whether it’s currently legal and the attorney general refusing to investigate American interrogators who have used the technique on terror detainees.

Vice President Dick Cheney, meanwhile, said “it’s a good thing” that top Al Qaeda leaders who underwent the harsh interrogation tactic in 2002 and 2003 were forced to give up information that helped protect the country.

In 2006, the CIA banned waterboarding by its personnel in the wake of a Supreme Court decision and new laws on the treatment of American detainees. “It is not included in the current program, and in my own view, the view of my lawyers, and the Department of Justice, it is not certain that that technique would be considered to be lawful under current statute,” Mr. Hayden told the House Intelligence Committee.

Hours earlier, Attorney General Michael Mukasey pushed back against Democrats on the House Judiciary Committee demanding to know whether he would prosecute American interrogators who used waterboarding in the past. He said the Justice Department could not investigate or prosecute people for actions that it had authorized earlier.