Last spring, when Peter M. Lange, an assistant professor of Government, arranged a lecture tour of several American universities and research centers for a high official of the Italian Communist Party, he didn't envision any major obstacles.

Stanley H. Hoffmann, professor of Government, sent off an invitation letter, co-signed by three non-Harvard Italy experts, to Giorgio Napolitano, the cultural head of the Italian Communist Party, and all was set for a two-week visit. Or so it seemed.

But when Napolitano tried to get an entry visa, he was told to wait, and wait he did. As the date the trip was supposed to start rolled around, Hoffmann and Lange tried to find out from the State Department what the problem was. Helmut Sonnenfeldt, counsellor to the State Department, finally let Hoffmann know.

Sonnenfeldt explained that a law, passed during the height of the McCarthy period, forbids members of Communist Parties anywhere from entering the United States, unless the State Department recommends a waiver of ineligibility to the Justice Department. The law is apparently never applied to representatives of Communist Parties in power.