I've long felt the filibuster rule in the Senate could be challenged as unconstitutional, since it effectively denies the Vice President his constitutionally defined right to break a tie vote. But this lawsuit seems to have gone about it the wrong way. I would think the Vice President would have to sue, and he'd have to name as the defendant the Senate or the Senate Majority Leader or something like that. Instead, the liberal group Common Cause sued Joe Biden. On first blush this made absolutely no sense to me, but on consideration i guess the idea is that the Vice President is also President of the Senate (according to the constitution; in practice not so much). And some of the co-signers on the lawsuit were Democratic congressmen whose bills failed to pass in the Senate due to the filibuster. So the lawsuit wasn't quite as crazy as it first sounded to me. But they still lost the case due to lack of standing, since if Biden isn't claiming his constitutional rights are being violated, there's no legitimate grievance. So you'd really need the White House to bring this lawsuit. That's never going to happen, of course. And not just because of my usual "Democrats aren't fighters" complaint. Challenging the law on constitutional grounds is something mainstream people in either party would laugh at (although i wish Josh Marshal wouldn't relish the loss so much, especially since it lost on lack of standing instead of the merits).