This "Speech or Debate Clause" was most famously invoked in 1971, when Senator Mike Gravel called a late-night subcommittee meeting and entered the Pentagon Papers into the Congressional Record, liberating them for the public and thwarting executive-branch officials who insisted that they should be suppressed.

Today, it's CIA torture and mass surveillance of innocent people that the executive branch wants to hide. It's beyond dispute that Bush administration interrogation tactics were illegal, as is the fact, documented in FISA Court opinions, that the NSA knowingly violated the Fourth Amendment on many occasions. Yet there is a lot about torture and surveillance that Americans still don't know.

Using the Speech or Debate privilege to reveal abuses could be costly for a sitting senator, who'd risk being stripped of his or her clearance to see classified information or even expelled from the Senate for violating its rules. Udall is a lame duck, so his calculus is simpler. He only needs to ask himself what is right. What fulfills his obligations to his constituents, his country, and the oath of office he took to support and defend the Constitution? Preserving his ability to fight for civil liberties another day is no longer an option.

That frame is clarifying: He is now obligated to speak out. I do not reach that conclusion lightly. As a general rule, I believe legislators should be wary of revealing classified information, but the abuses being covered up are clear, radical and corrosive to a democratic society. Consider the details of the torture issue alone:

The crime is heinous.

The Obama administration is in clear, flagrant, longstanding breach of its legal obligation to investigate torture and to refer torturers for prosecution.

The Department of Justice employee tapped to look into the matter didn't even interview many torture victims.

The Senate Intelligence Committee spent millions of taxpayer dollars and years of its staffers' time producing a 6,300-page report on CIA torture that is being suppressed years after being completed as the CIA itself influences it.

The current head of the CIA was himself a high-ranking staffer at the agency during the torture years.

CIA employees spied on the Senate oversight committee as it completed the report.

Until and unless the report is released, the prevailing narrative on torture will remain influenced by the misleading propaganda of torture proponents, increasing the chance that the U.S. will adopt immoral, ineffective, illegal interrogation techniques in a future war or national emergency.

Establishment voices believe Udall should wait for the CIA and the Senate to finish their negotiations about what parts of the report ought to be released to the public. Nonsense. The fact that the CIA is a party to negotiations about what parts of a report into its own criminal misconduct will be suppressed is itself an absurdity, and suggests that the CIA already has undue influence over U.S. politics.