ONE OF THOSE perennial attempts to reform Congress by limiting the terms of its members was trotted out again this week before a Senate Judiciary subcommittee. Under consideration are two constitutional amendments that would limit the service of future senators and representatives to 12 or 15 years. Proposals like these have been floating around at least since 1951, when the Constitution was changed to restrict presidents to two full terms. We hope they continue merely to float and don't light.

It needs to be conceded that proponents of amendments like these, introduced by Sens. Dennis DeConcici (D-Ariz.) and John C. Danforth (R-Mo.), are focusing on a real problem: the stagnation that prolonged terms in high office can produce. The seniority system, even though it is not so strong now as it once was, places enormous power in the hands of longtime members of Congress solely because they have been there so long. That, coupled with the political advantages that incumbency generates, makes it increasingly difficult for new blood to fight its way to Washington. Even when a veteran member has dropped out of touch philosophically with his constituents, he is often able to stay in office because party officials prefer power to issues.

Sen. DeConcini also argues that this distribution of power operates to deny equal representation to voters in states and districts where hot political competition makes it difficult for any person to stay long in Congress; the representatives of those areas are never able to stand on an equal footing with those from districts that send back the same legislator election after election.

Those are valid and appealing arguments. They make the proposed limits on congressional terms seem attractive. But the senators have traced the problems to the wrong source and are thus prescribed the wrong cure. The evils - and they are that - of which they speak grow out of unlimited service but out of the way in which Congress itself has chosen to treat that service. The cure, then, is not to keep particular people out of Congress, but rather to limit the power and prerogatives that Congress grants to those members who win reelection repeatedly. For example, restricting the length of time a member could be a committee chairman or, even, serve on one committee might not change the situation as much as would the proposed amendment, but it would certainly reduce the advantages of long service.

To attack this problem the other way, as the proposed constitutional amendments to, is to place an additional restriction on the right of voters to choose whomever they want to represent them in Washington. That right of choice is so fundamental that it should not be tampered with. Voters should be allowed to elect - and reelect - to Congress whom they please.