What is the simple majority vote that the Republican-controlled Senate is using to confirm Amy Coney Barrett to the Supreme Court?

A simple majority in the Senate is 51 votes, just one more vote than half the number of senators. But voting in that chamber of the legislature is anything but simple.

A supermajority of 60 votes is required to end debate on bills and to pass legislation. As per the Constitution, two-thirds of senators, or 67, are required to pass bills to override a presidential veto. Likewise, motions to amend the Constitution require 67 votes.

But the Senate makes its own rules for anything else the Constitution doesn’t spell out. And that’s where the so-called nuclear option comes in. Back in 2013, Senate majority leader, Democrat Harry Reid, was frustrated by Republican filibustering over President Obama’s nominees to several senior positions in the cabinet and in the federal courts. So, Reid changed the standing rule that normally required 60 votes to end a filibuster with a simple majority vote. Reid got Democrats to go along with the plan, and by a 52-48 vote, they upended four decades of Senate tradition. They changed the rule to lower the threshold to 51 votes to end debate, or break a filibuster. However, that rule change only applied to most presidential nominations—not those for the Supreme Court—and still required 60 votes for the final confirmation vote.

Republicans decried the rule change then, but have been making even bolder use of it since. When they gained control of the Senate in 2017, it was their turn to face Democratic filibustering of President Trump’s nominee to the Supreme Court. Then Senate majority leader, Mitch McConnell, got his fellow Republicans to go along with another rule change. Incidentally, by 52-48, they lowered the threshold for confirmation of the nominee, not just an end to filibuster, to a simple majority.

Republicans have been reaping the benefits of that rule change to confirm not only that first Trump nominee to the Supreme Court, Neil Gorsuch, but also Brett Kavanaugh and now Amy Coney Barrett. Simple, right?

France’s experience with a simple majority brings this questionable practice into focus. The National Convention in France was created in August of 1792 after insurrections led the previous legislature, the National Assembly, to abandon hopes of a constitutional monarchy. Representatives were elected to draft a new constitution. The result, the Convention, was a legislature that ushered in the country’s first republic. It was only a couple years after Americans made theirs.

The Convention had already voted to strip King Louis XVI of any remaining powers and punish him for his attempt to flee the country. With a simple majority of 361 to 360 votes, they then condemned him to death. It was unexpected that the fledgling legislature could do this in the midst of the French Revolution. Other options included detaining the king until peace settled within France and with her foreign enemies, then banish him from the country. Cooler minds, however, did not prevail. The majority got what they wanted with just one vote, though in the absence of a separate executive branch. They had taken on that role and even created their own judicial branch, too. Americans might like to think their system of checks and balances immunizes them from a similar fate. However, it was the US Supreme Court that landed George W. Bush his victory in the 2000 election.

A simple majority cost Louis XVI his head in January 1793. The Convention soon began delegating too much power to one of its committees, the Committee on Public Safety, where one delegate in particular, Maximilien Robespierre, assumed dictatorial powers. That fall of 1793 began the Reign of Terror, a radical period of the French Revolution that included massacres and public executions in the tens of thousands, many without facing a trial.

Considering voting thresholds for major political decisions, a simple majority can sometimes turn out to be anything simple.