When Congress investigated the Iran/Contra scandal twenty-two years ago, the Republican Representative from Wyoming argued that in matters of national security, executives should do as they please–the legislative branch be damned. This radical position, so completely at odds with the system of checks and balances established by the framers, might have been lost to history except for the fact that the Wyoming Congressman would eventually become the most powerful vice president the nation has ever known. It has long been evident to many that Dick Cheney’s refusal to “bear true faith and allegiance” to the Constitution did much to define the Bush/Cheney co-presidency. Until recently, however, it seemed unlikely that Cheney and his lieutenants would be held to account or that the proper constitutional balance would be restored.

Even after Bush and Cheney left office, Democratic Congressional leaders proved unwilling to tackle Cheney’s abuses or the issues raised by them. President Obama, fearing a protracted inquiry, said he wanted to “look forward.” But that stance grew difficult to maintain as revelations about deliberate assaults on the rule of law kept coming. After CIA director Leon Panetta informed Congress in late June of an illegal covert program that had been concealed from Congress, news reports outlined how Cheney had ordered the agency to keep the House and Senate intelligence committees in the dark.

The balance started to tip against Cheney. Senate majority whip Dick Durbin said there “absolutely” must be an Intelligence Committee investigation of the operation–which reportedly involved assassination plots. Intelligence Committee chair Dianne Feinstein, usually cautious, said Cheney operated “outside the law.” Russ Feingold, another committee member, who also chairs the Judiciary Committee’s Constitution subcommittee, said the program was “a violation of the National Security Act” and that people “who ordered that Congress be kept in the dark should be held accountable.”

At the same time, Attorney General Eric Holder signaled a new openness to investigating the Bush regime’s interrogation practices. Such an inquiry would focus on abuses other than the covert CIA program, but the constant appears to be Cheney, whose office has repeatedly been linked to the previous administration’s torture fetish.

It is clear that inquiries should proceed on all fronts, not from a desire to “get Cheney” but from recognition that accountability is necessary if we are to restore the system of checks and balances. Even if Holder appoints a prosecutor, Congress still has a duty to engage. As Tim Weiner, author of the National Book Award-winning Legacy of Ashes: The History of the CIA, argued in these pages in June, “Congress has a responsibility to oversee the CIA that remains largely unfulfilled. It has to ask the right questions, demand full answers and report the facts annually to the American people.” All too often, Congress has abandoned this duty, not only during the Bush administration but during previous ones, of both parties.

The investigations should be broadly defined, but their purpose made clear. If a vice president ordered the CIA to deceive Congress, he broke the law and violated his oath of office. The only way to assure that this “should never, ever happen again”–Feinstein’s goal–is to hold him fully to account. Anything less would lend dangerous legitimacy to Cheney’s imperial project. His machinations confirm the wisdom of having Congress members–and attorneys general–swear an oath to defend the Constitution from threats foreign and domestic.