WE RETURN TODAY to a familar complaint of ours: the injustices still being done to veterans who served in the era of the Vietnam War. We have in mind injustices deriving from, among other things, the lack of job opportunities, the stigma of service in a profoundly controversial conflict, the inadequacy of education benefits, the once-over-lightly approach to the upgrading of "bad-paper discharges" - and, above all, the shameful incapacity of so many members of Congress to stand up to pressures from powerful, old-line veterans organizations heavily weighted in their membership and their priorities to the veterans of earlier wars. We will spare you today a discussion of what may or may not account for the tendency of so many people, in general - and so many public officials, in particular - to turn away from this unfinished business of the Vietnam War. The point is simply that the tendency is there, and it is nicely illustrated by the trouble the Carter admininistration is having in Congress with a relatively modest provision in its program for civil-service reform that attempts to narrow and refine the present system for awarding sweeping and repeated government job preference to veterans.

The idea, quite simply, is to concentrate job preference on those who need it the most: the 7 million Vietnam-era veterans with no disability, and the 2.2 million disabled veterans of all wars.

Now, it is true this reform would reduce the job preference available to older, able-bodied veterans of, lets us say, World War II or the Korean War.It would also severly limit the prefence awarded retired veterans who made the armed services their career. Those are the veterans who make up the bulk of the membership of the American Legion, the Veterans of Foreign Wars and the other mainstays of the veterans lobby.

But they are also the veterans who need job preference the least - who have already in many cases used their preference more than once, sometimes to shift from one government job to another. For most of them, the original purpose of job preference - to ease their readjustment to civilian life - has long since been achieved.Some limit on their continued preferential treatment, what is more, would provide more job opportunities not only for those who served in Vietnam but also for a host of non-veterans - women, for example, and minorities - who are also supposed to be entitled to go to the head of the line.

This is, in short, a civil-service reform long overdue. And yet a modified version of the administration proposal was knocked out of the administration's civil service reform bill by a narrow vote of the Senate Governmental Affairs Committee. It's chances of revival on the Senate floor are uncertain, at best, which leaves its fate largely up to what happens in the House. The House Post Office and Civil Service Committee approved the modified administration proposal, and the administration has accepted a refinement sponsored by Rep. David E. Bonior (D-Mich.) that would give veterans who actually served in the Vietnam theater more time to use their preferences. The Bonior amendment is likely to come up for a vote on the House floor today, and it ought to be approved. Also up for a vote, probably today, it an amendment by Rep. James M. Hanley (D-N.Y.) that would substantially undo all the contemplated improvements in veterans preference and retain most of the injustices of the present law. We need scarcely add that this latest effort to walk away from the unfinished business of Vietnam should resoundingly rejected.