Congress’s most significant action this year was Senate Majority Leader Harry Reid’s decision to undo 200 years of precedent that requires a supermajority to change Senate rules. To speed the approval of executive appointments and judicial nominations, Sen. Reid resorted to raw political power, forcing a vote (52-48) that allows the Senate majority to change the rules whenever it wants. In a republic, if majorities can change laws or rules however they please, you’re on the road to life with no rules and no laws.

The supermajority safeguard that prevented senators from destroying the institution in which they serve is now largely gone. Gone also are members of the majority who understood the need to protect minority rights. There are no more Robert Byrds to quote Cicero, who said, “In a republic this rule ought to be observed: that the majority should not have the predominant power.”

Instead, we have a majority leader who has appointed himself a Rules Committee of one. Referring to the right of the minority to offer changes to bills under consideration, Mr. Reid said: “The amendment days are over.” Like President Obama, Mr. Reid is great at message discipline but weak on the rule of law and reality. His narrative about Republican obstruction of appointees is a diversion from his own war against minority rights. Even before his wrecking of the supermajority tradition, Mr. Reid had already used Senate rules to cut off debate and prevent the minority from offering amendments 78 times—more than all other Senate majority leaders combined.