IT MAY COME AS a puzzling surprise to many Montgomery County voters on Sept. 14, but there will be an important judge-judging exercise on the ballots. Four sitting judges on the Circuit Court for the county--well-qualified men and women who were elevated from the District Court by Gov. Hughes, acting on recommendations from the Judicial Nominating Commission for the Sixth Judicial District--now find themselves involved in a complicated election contest to remain on the bench for full terms.

There is no reason they should not continue serving. But unless voters in both primaries support all four--Judges Rosalyn B. Bell, James S. McAuliffe Jr., William C. Miller and Irma S. Raker--as a team, the whole exercise will have to be repeated in November. That's because there is a lone challenger who is seeking direct election to a judgeship--and he needs only to place fourth out of five in either primary to insure a rerun for the general election.

Peter Messitte is an active, nationally recognized lawyer who previously failed to win a recommendation from the nominating commission, a group made up of six lawyers, six lay persons and a chairman designated by the governor. It is this group that submits lists of candidates from which the governor makes interim appointments subject to later review by the voters. But Mr. Messitte is dissatisfied with the process by which the commission decides whom to recommend; he prefers political electioneering by competing candidates--sitting judges and challengers alike. Since this is possible under the current system, anyway, Mr. Messitte is running --and thus so must the judges.

The system should be changed--but not to encourage competitive political popularity contests and force judges to run for reelection. A person's politics should have nothing to do with his or her competence to be a judge. There is a better way: the sitting judge principle, under which judges run on their records instead of against opponents--and voters decide whether they want the judges kept in office or thrown out.

In any event, Judges Bell, McAuliffe, Miller and Raker have all served responsibly on the bench and are entitled to stay there. Each merits a vote on this section of the Sept. 14 ballot.