Filling a Court seat

 Under the Constitution, the president may appoint a candidate to fill a seat on the High Court and if the majority of the Senate agrees, that person sits.

Now as a Courtesy the rule was that 60 votes would be used in the senate. But the Constitution only requires a majority. Using  only a majority is called the "nuclear option" and Harry Read tht DEM leader of the SENATE at that time,  use the nuclear option to smash opposition  and cast aside that courtesy,,the dems had the majority at that time, to vote in PC judges and justices. He was warned that he would regret it  but he figured that his side could not lose, So the DEMS set the rules and now dont like their result.

Nothing in the Constitution limit the number of justices