A Simple Point
There seems to be alot of confusion around whether or not the Senate needs 51, 60, or 67 votes to change the filibuster rule. The answer is the former. Quite simple and it rests on a basic principle of majoritarian institutions: decision-making within a majoritarian institution is *always* and *only* subject to the majoritarian structure of the instituion. Specificaly, in regards to the U.S. Senate, there is NO vote that the Senate can take establishing *any* other standard than that which is proscribed in the Constitution. It is 50+1 and is *only* a different standard where the Constitution establishes such (such as on veto overrides).
Now, any Senate can establish a 'rule' for supermajoritarian (or non-majoritarian, for that matter) votes on any class of issues or personel. However, that rule is *just* as subject to the fundamental structure of the institution as any other vote on the floor. And the fundamental structure of the Senate is essentially the same as the House: 50+1. The only reason supermajority rules (and other rules, for that matter, such as the unanimous consent agreement) continue to persist from year to year is because *at least* 50+1 Senators agree that those should be the rules. So as long as 50+1 Senators think you need 60 votes to get judicial nominees through...then that's the number of votes that you need (leaving aside the issue of whether employing a supermajority requirement on judicial nominees interferes with the president's power to appoint judges to the courts). But as soon as we cross that 50 vote threshold where Senators no longer cling to such beliefs, then the only thing left is for them to give said beliefs effect. And there is *nothing* in the Constitution that should or can prevent them.
As, indeed, the Senate has done: changing the rules regarding filibusters several times in the last century. Indeed, cloture required, at one time, 67 votes rather than 60 votes. There seems to me no abiding principle that one could articulate that would permit a majority to reduce the cloture requirement on all issues from 67 to 60 yet would forbid a majority from reducing the cloture requirement from 60 to 50+ on a narrow class of issues or personel. However, even if we could come up with such a principle, it simply would not matter. It is beside the point. Because it is the institution itself that determines the how and the why of decisions and rules in a legislative body.
This becomes rather obvious when you contemplate what the Republicans could do to change the 67 vote requirement for a veto override. Clearly they cannot change it with a 50 + 1 vote because the 67 vote requirement is in the Constitution: part of the institutional structure of the Senate itself. A modification of the founding document is required in order to give effect to that wish. All potential actions taken in a legislative body are restricted by, and only by, the structure of the institution. Since the fundamental structure of the Senate is majoritarian, the rules put in place by Senators are only restricted as such. No decision *within* the institution (which the filibuster most certinaly was) can alter the institution itself. That must come from without. This is just as true for the *full* filibuster as well. The only thing *allowing* the filibuster of any legislative act is 50+1 Senators implicitly agreeing that there should be a 60 vote supermajority requriement to kill debate. Once that threshold is gone, so goes the filibuster entirely. An no amount of bellyaching will change the fact that this is perfectly appropriate and constitutional. D.GOOCH