In an explosive moment during the third day of Brett Kavanaugh’s confirmation hearing, Sen. Cory Booker threatened to release confidential documents related to Kavanaugh, noting that he acknowledged the risk of expulsion from the Senate.

The documents have since been released to the public, which begs the question: will Booker be expelled from the Senate? How would that occur, exactly?

Here’s what you need to know.

In Order For a Senator to Be Expelled, 2/3 of the Senate Has to Vote in Favor

These are the 4 documents marked committee confidential that I brought up in my questioning of Supreme Court nominee Brett Kavanaugh last night –> https://t.co/2RZkY2FS9a — Cory Booker (@CoryBooker) September 6, 2018

In order for a Senator to be expelled from the Senate, at least 66% of Senators need to vote in favor of expulsion. Though Republicans do have the Senate majority, it’s only by a few seats. This means that several Democrats would have to vote in favor of expulsion in order for Booker to be ousted.

Currently in the Senate, there are 51 Republicans and 49 Democrats. That means all Republicans and 15 Democrats would have to vote in favor of expulsion in order for Booker to be expelled.

The official rule that Booker broke was read aloud by Sen. John Cornyn: “Any Senator or office of the Senate who shall disclose the secret or confidential business or proceedings of the Senate, including the business or proceedings of the committees, sub-committees, and offices of the Senate, shall be liable, if a Senate, to be subject to the expulsion of the body.”

Booker immediately replied, “Bring it…bring the charges.”

It’s extremely rare for senators to be expelled from the Senate: only 15 have been expelled since 1789. What’s more, no senator has been forcibly expelled from the Senate since the Civil War, though a few have resigned in the face of charges of expulsion.

Booker also faces the option of choosing to resign, once faced with the Senate’s recommendation of expulsion.