The hard case for someone who supports the American purpose in helping El Salvador is Jean Donovan, the Catholic lay missionary killed there with three nuns in December 1980. How can the United States continue to sponsor a regime that may have had some hand in her murder and has yet to show it can carry off a trial of the military men suspected in the crime?

But this isn't the only question. The hard case for someone who opposes American policy is also Jean Donovan. How can the American enterprise in El Salvador be made to rest, as the foreign aid law and much comment on the case make it rest, on the country's handling of a murder whose victim defied repeated friendly pleas to leave a place where no authority existed to protect her from the violence unmistakably closing in?

Most people who ask the one question regard it as bad form to ask the other. But I find it necessary to raise both, and in that spirit I watched the television documentary "Roses in December--The Story of Jean Donovan," aired as the president was determining to continue sending El Salvador aid.

It poses only the first question--how can we support El Salvador?--and it does so with great power. Miss Donovan appeared to be a caring person aware of the risks she was taking, but driven all the same to "stand with the poor." This was enough to identify her and her colleagues as "subversives" to the Salvadoran power structure. Nothing in the film indicates any association that would justify her being called a "political activist," as Ambassador Jeane Kirkpatrick harshly termed her in a statement that she later corrected: "perceived" as a political activist.

The film's own politics come out tellingly as a narrator denounces "mindless murderers," while an American military attach,e toasts Salvador's defense minister. This image of American complicity in butchery dominates the perceptions of those who now wish to cut off aid.

I honor the impulse that makes people choke on this case. At a certain point, one makes a choice of what is important, and the weighing of pros and cons yields to following the logic of personal decision to its political conclusion: no other way seems open to respect either Miss Donovan's sacrifice or her cause.

Not everyone, however, is that sort of absolutist. Many of us remain relativists who feel more comfortable balancing things out, compromising, doing our best. The traps along this route seem not so total or irreversible as those along the other.

Miss Donovan understood instinctively, it seems to me, that in a society under such strain as El Salvador's the nonpolitical space shrinks to the vanishing point. For all of the insouciant American disregard she professed for her personal safety, I find it hard to believe she would have claimed her work had no political aspect. She was a responsible, clear-eyed adult who made a choice and could not have been surprised by its cost.

It does not follow that a proper mourning requires everyone else to accept the political end--a victory of the left in El Salvador--that seems to me the likeliest result of the success of the political campaign being waged in her name. To admire her valor, it is not necessary to accept either her implicit politics or all the political uses being made of her now.

The suggestion of American complicity in her death falls, I think, somewhere between unproven and false. It may well end up being impossible either to indict or clear the United States. It is as astonishing to me that El Salvador continues to move under foreign pressure toward a wartime trial of its own soldiers, as it is dismaying to others that the soldiers and assorted higher-ups have not already been convicted and the regime brought down.

I come out here: it is simply not possible for a lone American to go to a dangerous place, a society undergoing change, a foreign country, and to reap the rewards of engagement without also incurring the risks. The nation's foreign policy cannot be asked to carry the burden of one citizen's private choice.