The House rolled the dice by granting immunity to former Justice Department aide Monica Goodling to testify about the firing of eight U.S. attorneys.

Now, lawmakers must decide whether to bet on immunity again in the Jack Abramoff bribery investigation.

The stakes are high. A congressional immunity deal can scuttle a criminal investigation, as it did for John Poindexter and Oliver North, who had their convictions reversed in the Iran-Contra arms and money scandal after courts determined their cases were built too much on testimony they gave under a congressional immunity deal.

"By pursuing their investigation and bringing things to light, there's a risk that Congress will screw up a criminal investigation. That's not a nice thing to have to run on next election," said attorney Alan Baron, who served as Democratic counsel to the Senate Governmental Affairs Committee during its 1997 fundraising investigation.

But the payoff can be huge. Former White House Counsel John Dean's immunized testimony helped unravel the Watergate cover-up and force the resignation of President Nixon.

House Judiciary Committee Chairman John Conyers hoped for such a payoff Wednesday when he swore in Goodling under an immunity agreement. Goodling, the former White House liaison for the Justice Department, testified that she "may have gone too far," when she let politics play into the hiring of career employees.

She also disputed testimony by Deputy Attorney General Paul McNulty about his involvement about the U.S. attorney firings. She also recalled her discomfort during a private meeting with Gonzales in which he tried to review his recollection of events leading up to the firings.

What Goodling didn't provide was any support for Democratic lawmakers' assertions that prosecutors were fired to tamp down corruption investigations or as political retribution.

Susan Ralston, a former aide to presidential adviser Karl Rove, is asking for a similar deal from lawmakers before she'll answer questions about White House ties to Abramoff, who has been convicted of bribery. A two-year investigation into his influence peddling has led to the conviction of a congressman, several former House aides and two members of the Bush administration.

Joseph diGenova, a former prosecutor and legal counsel to several congressional committees, said Goodling and Ralston made the right decision — say nothing to a congressional committee without a promise the testimony won't be used by prosecutors.

"These are not hearings anymore. There's been a change in attitude from fact-finding to making accusations," diGenova said. "Through Democrat and Republican administrations, these hearings have become public grand juries. You have to make them work for the information because they have changed the rules."

While the decision might be easy for witnesses, it's harder for lawmakers and the Justice Department. Independent Counsel Lawrence Walsh, who investigated the Iran-Contra case, warned in his final report to Congress that immunity should be given sparingly.

"Future immunity grants, at least in such highly publicized cases, will likely rule out criminal prosecution," Walsh wrote in his report on the arms for hostages scandal that reached deep into the Reagan administration.

Lawmakers voted to offer Goodling immunity even though she is the subject of a Justice Department investigation into the U.S. attorney firings and whether politics influenced employment decisions.

"After balancing the significant public interest against the impact of the committee's actions on our ongoing investigation," the Justice Department said in a letter to lawmakers, "we will not raise an objection or seek a deferral."

Rep. Henry Waxman, D-Calif., chairman of the House Committee on Oversight and Government Reform Committee, said he has not decided what to do with Ralston's immunity request. He said he wants to seek information about Abramoff's ties to the Bush administration from other sources first.

If lawmakers decide to offer immunity, it could put the Justice Department in an awkward situation. If attorneys oppose it, they might appear to be blocking an inquiry into possible Bush administration corruption. If they agree to the deal, a possible witness in the criminal case will be subjected to questioning and cross-examination that potentially could damage a prosecution.

Ralston's attorney, Bradford Berenson, said there's no indication she is a target of the Abramoff investigation.

Since the Iran-Contra fallout, "Congress has been extremely wary of pushing forward with grants of immunity during criminal investigations" without Justice Department consent, said former Watergate prosecutor Richard Ben-Veniste.

The immunity question should be a tough one, diGenova said, because it forces lawmakers to weigh the benefit of a political hearing against the potential damage to a criminal investigation.

That's why he's adamant that "anybody with an ounce of brains involved in a scandal as a key witness" should demand immunity before agreeing to testify.

"If Congress wants to bite this apple," he said, "you make sure it's a poison one."