The choices -- dispel the cloud over the White House or impeach the president.

When the congressional Iran-contra committees decided to immunize Oliver North and John Poindexter, they were acutely aware of the potential consequences for any subsequent criminal trial. Those who maintain that the committees acted irresponsibly ignore not only the record, but the constitutional crisis that gripped Washington after the scandal erupted.

In November of 1986, the American people and Congress learned that the United States had secretly sold arms to Iran and that proceeds from these illicit arms sales had been diverted to the Nicaraguan resistance at a time when U.S. military aid to the contras was prohibited by law. The crisis triggered by these shocking reports held the nation in thrall. The administration lost public confidence. In a parliamentary system, the government would have fallen. Under our constitutional system, the president remained in office, but was staggered, as Reagan officials have acknowledged.

There were only two choices under our constitutional system: dispel the cloud over the White House or impeach the president. To accomplish either, the facts underlying the affair had to be found and disclosed as rapidly as possible.

A criminal prosecution does not serve that purpose. Criminal investigations take place in secrecy, and they take time. Criminal trails are hemmed in by strict rules of evidence designed to provide a fair forum for determining guilt or innocence, not to inform the public or to resolve constitutional crises.

Only Congress had the power to act quickly, decisively and openly. It was Congress's duty to do so. After all, it was Congress that had been misled. It was congressional oversight of intelligence operations that had been ignored. And it was Congress that had to decide whether an impeachment process should go forward. If Congress had chosen instead to pass the buck to criminal investigators, it would have been justly condemned for abdicating its constitutional responsibilities and playing politics with a nuclear tinderbox. On the other hand, if Congress had chosen to proceed behind closed doors, it would have been accused of perpetuating the very secrecy that had led to the affair.

Nonetheless, the congressional investigating committees did their best not to foreclose criminal prosecutions. To the contrary, it was a central purpose of the committees to uphold the rule of law. As their report concluded, "there is no place in government for law breakers."

Accordingly, the committees conducted their investigation with intense regard for individual rights as well as the independent counsel's requirements. Decisions to immunize witnesses were not made lightly. Immunity for North and Poindexter was deliberately deferred, at the independent counsel's request, to give him time to build his case and seal away the evidence before any possible taint. That is why Poindexter's deposition was conducted in private, and that is why Poindexter and North did not testify until near the close of the congressional hearings, by which point the independent counsel had been gathering evidence for nearly eight months. The District Court found these procedures adequate. So did one of the three appellate judges in the North case. The final word has yet to be written.

Certainly, the independent counsel would have preferred no immunity grants for North and Poindexter. But in that event, these two central figures would not have testified. And the daunting question of what they would say the president knew would have remained unanswered -- perhaps permanently, given Poindexter's decision not to testify at his own trial. The constitutional crisis would have continued unabated. Indeed, the independent counsel was unable to return indictments against North and Poindexter until the winter of 1988 or to conclude Poindexter's trial until 1990.

If in such circumstances Congress must make a choice between enabling the government to function or relying exclusively on criminal prosecutions, the choice Congress made in the Iran-contra affair was the right one. Arthur L. Liman and Mark A. Belnick were chief counsel and executive assistant to the chief counsel, respectively, to the Senate Iran-Contra Committee.