Q: Why can the U.S. Senate change the number of votes to end a filibuster by just 51 votes and not 60 votes?

—Hoke Kimball, Atlanta

A: The U.S. Senate can change the number of votes to end a filibuster – known as invoking cloture – because the ability to limit debate through cloture is a Senate rule. The U.S. Constitution (Article 1, Section 5) states that each House may determine the rules of its proceedings, which means the Senate gets to create the rules by which it operates.

Until 1917, senators could engage in unlimited debate through the filibuster, which is used to delay or block a vote. In 1917, the chamber passed Rule 22, creating the cloture procedure. If passed, cloture limits further consideration of an issue to 30 hours, effectively ending a filibuster. Originally, Rule 22 required a two-thirds majority vote of the Senate. In 1975, the Senate voted to lower the threshold to a three-fifths majority vote – or 60 votes.

In the recent cloture vote over Neil Gorsuch’s nomination for U.S. Supreme Court justice, Senate Majority Leader Mitch McConnell (R-Ky.) employed former Sen. Harry Reid’s (D-Nev.) so-called “nuclear option.” Utilized by the then-Senate majority leader in 2013, it allows the Senate to sidestep Rule 22’s 60-vote requirement through a parliamentary procedure.

In the Gorsuch case, McConnell addressed the Senate presiding officer on a point of order, asking that the threshold to end debate on U.S. Supreme Court nominees be lowered from 60 to a simple majority of 51. As with Reid in 2013, McConnell’s point of order was initially overruled, but he appealed the ruling and won in a 52-48 party line vote. That new rule changed the 60-vote minimum to end debate on U.S. Supreme Court nominations to 51 votes.

Fast Copy News Service wrote this column; Keith Still contributed. Do you have a question? We’ll try to get the answer. Call 404-222-2002 or email q&a@ajc.com (include name, phone and city).