The democratic process has produced a perverse result in El Salvador. Reform is on the defensive. Its advocates in the political parties came up short in the new constituent assembly, and its supporters in the armed forces must now throw their weight around to compensate. Meanwhile, some of the more suspect elements of the old hard right are in the catbird seat. They have the seats in the assembly and they can invoke the very fairness of the elections to discredit the proponents of reform, who include the opposition politicians, many top army officers and, not least, the United States.

A respected independent, economist and banker, Alvaro Magana, has been confirmed as the provisional president of the government. But he got his job not through the Salvadoran civilian political process but through intervention in that process by reform-minded officers and by diplomats and congressmen of the United States. The body that confirmed him, the constituent assembly, seems firmly in the grip of former major Roberto D'Aubuisson, known in the past chiefly for his death squad connections and his attempted coups. Under him, the assembly (the legislature) has repealed the decree authority the old junta used to introduce reforms, and has voted itself powers that conceivably will enable it to thwart the provisional government (the executive). Meanwhile, the assembly will be writing a constitution and organizing new elections.

Reagan critics had warned that El Salvador, caught up in war, revolution and violence, was not ready for early elections, especially for elections in which the excluded left would not be available to offset the resurgent right. The administration may have been overconfident, but it felt that the prospect of building a more democratic base made the risk worth taking.

It seemed a reasonable risk to us, too, and we still feel that way. To see why, it is necessary to go back to the stunning turnout of March 30. Although parties of the old order profited from it, it is inconceivable that the Salvadoran people were voting to restore the old order. They were responding perhaps to the right's promises to end the war and "improve" the reforms, but they were not inviting back the oligarchy whose misrule created the crisis rending their lives.

Peace and reform are what Salvadorans demanded on March 30. Mr. D'Aubuisson should not misread his mandate. If the administration does not hold him to it, Congress surely will.