The decision to hold an emergency Commons debate on the ramifications of the new European (not EU) treaty is important on several levels.
First, it underlines that, with a more open system in the Commons, it is no longer possible for governments and Oppositions to collude to prevent prime-time debates on euro-issues. With a Backbench Business Committee and a Speaker more willing to allow backbench applications for emergency debates, the old silence strategy is no longer viable; the Commons cannot be prevented from airing its views on the European treaty - or pretty much anything else.
Indeed, I hear government whips are now positively encouraging euro-debate; and Tobias Ellwood, PPS to the Europe minister, David Lidington, is even organising trips for backbenchers to see for themselves what is going on in the EU institutions. The thought is that if euro-debate is a regular occurrence, rather than an Armageddon, only secured by Byzantine procedural cunning, then much of the heat will be taken out of the issue.
Yesterday's motion to hold the debate was a carefully organised coup - with supporters working hard to line up cross-party support without tipping off the whips. An application of this kind is made through a three minute speech - in this case from the elder statesman of euroscepticism, the Conservative Bill Cash. The Speaker then decides whether it can go ahead, but then at least 40 MPs must stand up in the chamber in support.
Rather more than that stood up on the day - and I suspect a good part of their motivation was simply to assert their power to debate what they choose, and underline that they are no longer totally in thrall to the government.