THE TRUSTEES of the fledgling University of the District of Columbia made a difficult choice last week when they turned down an opportunity to take over Antioch Law School. Students, administrators and friends of Antioch, who have supported the innovative school through 12 years of turmoil, are disappointed. But the trustees' first responsibility was to UDC, and they asked the right questions. Did the university need a law school at this stage of its development? Could one be sustained at UDC? And are the taxpayers of this city best served by absorbing and subsidizing a law school instead of investing more money in the public schools?

The whole idea of a law school at UDC would have seemed preposterous six months ago. But the proposal was made in an effort to save Antioch, an innovative school dedicated to turning out public-interest lawyers. The school had recently lost the financial support of its parent university in Yellow Springs, Ohio. In addition, and in part because of funding difficulties, an American Bar Association committee has cited deficiencies in academic standards and facilities in recommending that accreditation be withdrawn. A final decision will be made this summer by the ABA's House of Delegates, but loss of accreditation would bar graduates from taking bar exams in most states and in the District of Columbia.

A number of outstanding lawyers and public figures in this community have sought to save Antioch because they believe it fills a special need in emphasizing service to the poor. Among the school's benefactors is the Eugene and Agnes Meyer Foundation, which has supplied space for the school's library for $1 a year. Certainly, it is not a reflection on the school's credentials, its objectives or its supporters to decide against a merger with UDC. But UDC's trustees were correctly concerned with the future of the public university, and it is already beset with many problems of its own.

The law school needed millions to renovate facilities and more to subsidize its operation. About $7 million in city funds would have been required to sustain the merger in the first 15 months. The D.C. Council, last March, had authorized only $1.3 million. The university itself is short of funds now. Enrollment is declining, a large layoff of nonfaculty personnel has been ordered, and cutbacks in the teaching staff are expected next year. The vote against a merger was unfortunate for Antioch, but prudent from the standpoint of UDC.