Geof Stone on the Nuclear Option in the Senate
Why did the Democrats in the Senate enact the so-called "nuclear option"? In the Senate, unlike the House of Representatives, a minority of Senators can prevent a vote on proposed legislation, presidential nominations or other legislative action by engaging in a filibuster. Traditionally, as in the wonderful James Stewart movie Mr. Smith Goes to Washington, this meant that a senator could "hold the floor" of the Senate and prevent a vote on a pending matter for as long as he could keep talking. The filibuster was perhaps most famously used by Southern Senators to block civil rights legislation.
In more recent years, the Senate amended its rules to permit a Senator to effect a filibuster without actually having to do the talking. For all practical purposes, all a Senator now has to do to implement a filibuster is to say that he is filibustering. The only way to end a filibuster is by a cloture vote - that is, a vote to "close off" the filibuster and let the matter come to a vote. In the modern era, 60 votes (out of a possible 100) are required for cloture. Thus, a Senator can now prevent the Senate from acting on proposed legislation, presidential nominations or other legislative action as long as there aren't 60 members of the Senate willing to invoke cloture.
Although the filibuster obviously can be abused, it has traditionally served a useful role. Fundamentally, it was designed to permit a minority of the members of the Senate who care deeply about a particular issue in extraordinary circumstances to prevent the majority from having their way. It is one of the many checks-and-balances in the American constitutional system designed to protect minority interests.