HUMAN RIGHTS policies fall into the category of things that governments ought not to attempt at all unless they are prepared to pursue them forthrightly. Nothing excites cynicism and boredom more rapidly than high-minded principles that are applied energetically in certain selected cases and not at all in others. And yet an American government can hardly avoid having a human rights policy. It is, after all, no more than a bureaucratic label for the central characteristic theme of American diplomacy, when American diplomacy is at its best.

The Reagan administration is now going to try it again. So far, this second approach to the subject seems to be off to a somewhat more promising start. The first time around, the Senate Foreign Relations Committee's specific objections to the nomination of Ernest W. Lefever were reinforced by broader doubts about a policy that promised to favor, stridently, governments of the right. This time, to support the nomination of Elliott Abrams for the human rights job in the State Department, the department has published a memorandum setting out a larger view of the subject.

The memorandum, bearing the imprimatur of the secretary of state, sets the right balance. A concern for political liberties is the essence of this country's opposition to the Soviet Union, the memorandum argues, but the policy has to be more than a polemic weapon against the Russians. "If a nation, friendly or not, abridges freedom," it declares, "we should acknowledge it. . . ." But there is also the danger, with which the Carter administration never dealt gracefully, that the policy can turn into mere finger- pointing and deprecation of erring foreigners by virtuous Americans. "We must take into account the pressures a regime faces and the nature of its enemies. . . ," the State Department suggests. That's true, but there's a welcome recognition, a few lines further, that "crime control equipment" should not be sent abroad without regard to the ways in which it's going to be used.

The real meaning of policy lies in its actual application to the hard cases. A deputy assistant secretary of state, Peter Constable, was testifying yesterday before a House subcommittee on some of the hard cases. What about Pakistan? Soviet operations in Afghanistan have made it profoundly important to the security interests of many other countries, including this one. Pakistan has supported human rights by giving sanctuary to more than 2 million Afghan refugees, Mr. Constable observed. On the other hand, Pakistan is run by a military government under martial law. That military government needs help. The United States is responding with both military and economic aid. Mr. Constable assured the subcommittee only that the State Department will continue to weigh considerations of human rights along with the other elements of foreign policy. Under the circumstances, sensible diplomacy couldn't promise much more. In the end, it isn't the testimony and the memorandums but the performance that will count.