I wouldn't call the current court a rubber stamp. There have been some very unfortunate decisions, sure, but there were also quite a few decisions that prevented either the states or the feds from running wild.

The real problem with being a true check is partisanship on the court. By now, it seems to be essentially accepted that there are "liberal judges" and "conservative judges", and that they will rule accordingly. I cringe every time I hear that, because SCOTUS, like any other court, is supposed to rule on what the law is, not on what it should be; and one's political affiliation should not affect the former. In practice, of course, it does matter these days, and it is a really bad thing, especially in an institution that is 1) so small, and 2) not providing any mechanism to hold them responsible.