FOR THOSE partial to such occasions, we should note that 1981 marks the 15th anniversay of the passage of the Freedom of Information Act (FOIA). As if to recognize that milestone, both supporters and critics of the statute already have begun preparing for the first comprehensive debate since 1974 over its use and abuse.

Consider the signs. Last month, the attorney general terminated the Carter administration's more liberal "demonstrable harm" standard for evaluating release of documents under the FOIA and, at the same time, requested proposals from all departments and agencies for changes in the law. In mid-July, both Senate and House subcommittees, the one Republican-controlled and the other Democratic, plan almost simultaneous hearings on FOIA revision. Throughout Washington, interest groups representing every view of the measure have begun preparing for the major legislative battle, expected sometime this fall, over amending the FOIA. One group of FOIA enthusiasts reportedly has even planned a Fourth of July "birthday party" to publicize its achievements.

At this point, the administration has not yet shown its hand or indicated the precise scope of changes in the FOIA that it may seek. To solicit ideas from the various FOIA units throughout the bureaucracy buys a certain amount of time; the Carter administration, after all, dawdled away its final two years with just such a "comprehensive review." Unlike his predecessors, however, the attorney general confronts a Republican-controlled Senate eager to revise the statute in order to limit access (among other things) to the records of law enforcement, intelligence and business regulatory agencies.

Virtually all the proposals now being discussed would narrow significantly the boundaries of public access under the FOIA, a result that disturbs supporters of the measure and understandably so. As it turns out, the two sets of mid-July congressional hearings -- one by Sen. Orrin Hatch's (R-Utah) Senate subcommittee on constitutional rights and one by the House subcommittee on government information and individual rights, chaired by Rep. Glenn English (D-Okla.), undoubtedly will be contrasted as anti -FOIA and pro-FOIA forums, respectively. If, however, both subcommittees fulfill their assurances that a broad and balanced cross-section of witnesses will be invited to testify, the comparision may prove simplistic and unwarranted.

As for Justice Department, when it finally submits its specific recommendation for FOIA revision, this might be done most usefully in an omnibus package rather than allowing all agencies to negotiate separately with Congress. In the months ahead, we intend to watch closely the evolving debate, particularly to see if (in the deputy attorney general's words) the proposals that emerge not only correct what critics have called the statute's "unintended uses" but also improve the handling of "requests for information that would serve the goal of better informing the electorate." Whatever changes may be required in the act, in short, on balance the FOIA has demonstrated its usefulness and must not be gutted.