NO ASPECT OF POSTWAR Amrican policy is more shameful than the refuge given known and suspected Nazi was criminals who exploited anti-communism to escape justice in their homelands. Of the scum - if that is not too mild a word - who have benefited from this lapse, Andrija Artukovic may be the most notorious. As a minister of interior in the fascist puppet state that Hitler set up in occupied Croatia, Artukovic directed the murder of 600,000 or more Serbs, tens of thousands of Jews and numerous gypsies, among others. After the war, he slipped into this country under a false name. Unmasked, he managed to avoid deportation by claiming, with Immigration and Naturalization Service approval, that he would be politically persecuted by the Communist regime in Yugoslavia.

The INS, in a new ruling, has now said that the prohibition on deporting aliens who might be persecuted for their politics does not apply to persons considered to have committed war crimes. So Artukovic, who is 76 and lives near Los Angeles, faces deportation anew. That he does, that deportation or denaturalization proceedings have been begun against eight others believed to be war criminals, that the cases of still 80-odd others are being investigated, that one person (the first) actually was extradited for accused war crimes last year - all this is cause for sober satisfaction. The grip of reflexive anti-communism had to weaken for this to happen. Great personal tenacity and dedication had to be shown by a handful of people in the bureaucracy and by a few fire-setting politicans, including Reps. Joshua Eilberg and Elizabeth Holtzman and others.

It assaults one's senses to think that people accused of committing the vilest crimes known to man could have enjoyed liberty and a good life in American for so many years. Therein lies the basic reason why those so accused should, after being accorded due process, be deported for trial. The sooner the review is completed, moreover, the stronger will be the United States' position to demand that other nations harboring war criminals, and nations harboring political terrorists of a more recent vintage, yield them up to the law.