From the time that cloture rules were introduced into the Senate in 1917, until the end of Reagan's presidency, the filibuster was deployed 385 times. During Obama's presidency, Senate Republicans launched over 500 filibusters, many of them to directly block Obama's appointments to the federal bench. In Republican hands, the filibuster ceased to be a tool of checks and balances, and became a tool of obstruction, or better yet, nullification.