YOU HAVE TO SAY that when the Democrats in Congress finally get around to creating new judgeships, they do it with a bang. Last Monday, the House passed a bill to create 145 of them. Once the horse-trading with the Senate (which approved 148 last spring) is completed, the total is likely to be around 150. That's not bad when you consider that there are now only 495 judgeships.

These new judges aren't all needed, at least not now. We suspect that 15 or 20 - all district judgeships - could be eliminated and wouldn't be missed. But given the way Congress has treated the courts in recent years, this sudden burst of generosity is under-standable. It is a kind of compensation for years of neglect. Back in 1972, the Judical Conference said 51 new district judges were needed. But Congress procrastinated; the number of needed judges increased steadily as caseloads went up; and the courts fell further and further behind with their work. Why the procrastination? Well, first there was Watergate, and the House Judiciary Committee was busy. Then there was an election on the horizon, and the desire to save these plums for a Democratic president was irresistible.

Having chosen to treat the needs of the judicial branch so cavaliery, Congress should do something beyond increasing the number of judgeships to make up for its neglect. And the bill the House passed contains a provision that might just be that something. It directs the president to establish procedures and guide-lines for the selection "on the basis of merit" of nominees for the new district judeships. While the procedures wouldn't be binding - the president could waive them at any time, although he would have to tell the Senate why - they might be a start toward ensuring that only highly qualified persons get the nominations.

Naturally this idea does not sit well with some members of the Senate. They have come to regard the selection of new district judges as part of their political patronage, if not actually a God-given right. On more than one occasion, a president has been forced to nominate a less than fully qualified person because a powerful senator insisted. Other members of the Senate know this practice is wrong. Some have set up their own citizens committees to recommend nominees. If the House will stand firmly behind its proposal, the time may be right for expanding that kind of selection process to include all federal judges.

There should be no mistake about what will come out of a merit selection system even when it operates at its best. It is not likely to produce many Republican judges when a Democrat is in the White House or vice versa. Given two candidates of comparable ability (and in picking judges the field is never that narrow), a president will rarely award a lifetime job to someone who opposed his election or his party. There is nothing inherently wrong with that; the spoils do go to the victors. Merit selection as it would apply to the 150 or so new federal judges won't stop president Carter from packing the bench with Democrats. That could make a difference in the quality of justice.