Chris, thanks for the comment! The only point I want to quibble with is the assertion that “the Senate can repeal or modify treaties.” I’m not sure why you say that. Congress can enact a law that abrogates a treaty, and if it does so, then as a matter of US law the latter-enacted law governs. But I don’t think the Senate can act on its own. Moreover, even though Congress has the power to do this, it would be a violation of international law, which permits amendment of a treaty only by agreement of the parties (Vienna Convention art. 39) and which permits termination of a treaty only in accordance with the treaty’s own terms or by agreement (art. 54). The MLAT (art. 20) provides for termination of the MLAT by six month’s written notice, but that would not be a matter for Congress (or at least for Congress alone).

A sharp post, and there’s nothing here that I disagree with. You’re right that Schumer’s letter is a political maneuver rather than a legal maneuver, and I meant to evaluate it in those terms, though I certainly could have been clearer about it. Schumer didn’t file an amicus brief, or offer an affidavit to be filed with the court, trying to join an effort to have the subpoenas quashed; rather, he wrote to the Secretary of State (and the AG) and argued for the executive branch to withdraw the subpoenas and do the diplomatic work to get the British to agree to that.

So I wouldn’t say that “the legislative history of the treaty shows that the subpoenas are impermissible,” but I would say that the legislative history of the treaty shows that the subpoenas are highly inadvisable and politically reckless. And I hope that one of the results of the BC subpoenas is that the Senate takes a much closer look at what MLATs allow governments to do.

The executive branch carries laws beyond the intention of the legislature often and successfully. I’m not a lawyer, but my understanding is that, for example, the RICO laws were created to give prosecutors a weapon against the Mafia. Over the subsequent decades, though, they’ve been used far more widely, against many other kinds of organizations. I’m sure you can think of many more examples.

So here we have a senator saying that hey, hold on a minute, this is not what we had in mind when we ratified this treaty. The fact that the wording of the treaty doesn’t reflect what Schumer and other senators are saying about the appropriate use of the US-UK MLAT may not impede these subpoenas in court. But if the executive branch charges down this road without bothering to notice the objections from senators, they may create a political problem—I hope they’ll create a political problem!—that will lead to restrictions on the breadth of MLATs. The Senate can repeal or modify treaties. If the executive branch is going to abuse its discretion w/r/t these treaties, I hope the range of that discretion will be narrowed. The aggressive language of the government’s briefs in this case are a bright flashing light calling for a political reevaluation of the power we’ve given to the executive branch.