About 20 radical Law School students formed a picket line in front of the Law Placement Office yesterday while three recruiters from a prestigious New York law firm interviewed prospective trainees.

This is the first time anything like this has ever happened here," said Miss Eleanor Appel, head of the placement office, which is located at 23 Everett St.

The protesting students charged that the law firm--Milbank, Tweed, Hadley, and McCoy--oppresses the black people of South Africa by supporting their government. The firm represents the Chase Manhattan Bank.

The students handed out a pamphlet which stated that the firm, "through its work as counsel and through the power and financial interest of its partners has played a leading role in furnishing American economic and political support to South Africa."

The demonstrators, mostly first-year students, all belonged to the Radical Law Students Group, which was formed this semester and has more than 60 members.

The recruiters had stated that they would address the crowd of demonstrators and onlookers at 12:40 p.m. But when the recruiters left the building at 1 p.m. instead of talking to the students, they walked through the picket line saying only, "We have nothing to say at this time."

The law firm was seeking ten second-year students to work for two weeks this summer. Fifteen students made appointments to speak to the firm's representatives. Four cancelled their appointments, including one student who said he broke the appointment because of the firm's South African affiliations.

Just before the demonstration Michael J. Horaz 2L, one of the radical students, and Joseph E. Leininger, vice-dean of the Law Faculty, had a reportedly heated dispute over the placing of protest signs in the second-floor windows of the Placement Office.

The windows are part of the offices of the Students Bar Association which, according to the group's president, David N. Rockwell, 1L, had given the radical students permission to use the windows during the demonstration.

Haroz described the incident: "Leininger threatened me with force to take the signs down, although the only force he used was to put his hand on my arm." He added that this was "legally an assault."

The dean, asked if any force had been used, refused to comment. He said only that "on learning that signs about the boycott were on display, I took them down. They were then put back up." During the demonstration Haroz announced that he was planning to sue the dean.

Although the law firm's alleged connections with the South African regime caused the demonstration, radical students are critical of the entire recruiting program. Robyn Cooper, IL, treasurer of the Student Bar Association and an active member of the radical group, complained about the program stating that "the recruiters never respond to your questions, never tell you anything about the firm's policies."

Some members of the radical Law students favor no on-campus recruiting at all.

The Law School's Joint Student-Faculty Committee also is studying ways to improve the present recruiting system. The Committee is investigating ways of disseminating more relevant data about the firms and holding joint meetings of the interviewer and students before the individual interviews.

The Harvard Bar Association challenged Milbank, Tweed, Hadley and McCoy, to debate on Thursday, but the firm said it couldn't fit the debate into its schedule