The retirement of Justice John Paul Stevens marks the end of many eras.

On the current court, he is the last justice to have served in the military and the last Protestant.

It may not mean much judicially, but he will probably be the last Supreme Court justice ever to have seen Babe Ruth play baseball.

He is also a throwback to a time when political dividing lines were not as firmly drawn, and a Republican president could nominate someone who would became the leading liberal justice of his era, simply based on the judge’s legal qualifications.

By now, interests groups, senators and administrations have figured out the game and know the formula for getting a judge on the court. Successful nominees should be federal appellate judges because they have already gone through the confirmation process. And they should not have been on the appeals court long enough to develop a record of controversial opinions.

That has given us a court with eight former appeals court judges, all graduates of Harvard or Yale law schools. There are no former senators (like Hugo Black) or former governors (like Earl Warren) or even state legislators (like Sandra Day O’Connor) who would bring not only real-world experience, but a file of public statements that would make easy targets for political opponents to shoot at.

To top it off, because of the sharp partisan division in the Senate, this Supreme Court nominee will face the possibility of a filibuster, which hasn’t happened since 1968, when the nominee for chief justice, Abe Fortas, had pending corruption charges.

Barring revelations like that, the Senate should not stand in the way of this nominee getting an up-or-down vote. Republicans are almost certain to find something they do not like about whomever President Obama will select, just as Democrats objected to the last administration’s nominees.

The only way that the liberal/conservative balance on this court could change with this nomination would be if the person who takes Stevens’ seat becomes, over a long career, as much an ideological surprise to the president who makes the appointment as Stevens became for the man who named him, President Gerald Ford.

The country would be well-served if Stevens’ replacement is confirmed in a fair and open process that would open service on the nation’s highest court to people who would come to the job with a variety of real-world experiences. That era should begin now.