President Bok yesterday, employing a veto power he has never before used, reversed a decision by the Law School faculty to grant tenure to a visiting scholar, professors said.

By withdrawing the offer of tenure to Visiting Professor David Trubek, Bok overruled more than two-thirds of the faculty and Dean of the Law School James Vorenberg '49, who voted earlier this year to tenure the legal expert, who is considered to be an ideologically left-leaning scholar.

Faculty members said yesterday that Bok's action threatens to decrease the historic independence of the Law School. In addition several professors said the decision was a blow to academic freedom because it was based on ideological rather than scholarly grounds.

"It's modern day McCarthyism," said Professor of Law Gerald Frug, who supported Trubek's appointment.

In the past few years the Law School has become increasingly split between conservative scholars and those who are broadly grouped under the heading of the liberal movement called Critical Legal Studies (CLS). Tenure decisions have seen the most public evidence of this division.

Bok, a former dean of the Law School, wrote in a memo to the faculty two years ago that in order to protect the tenure process from becoming a political battleground, he would consider reviewing tenure decisions if asked by either camp.

Each Law School decision--like every University tenure decision--technically requires the president's approval. Before writing the memo, Bok had never publicly indicated a predilection to use this power at the Law School.

In interviews yesterday, faculty members said that the decision by Bok to overturn the offer to Trubek, coupled with other tenure moves in the past two years, constituted a pattern of unfair scrutiny of the work of those professors considered to be members of CLS.

Members of CLS hold that the law is not founded on abstract principles of justice, but is necessarily intertwined with dominant social and economic norms.

Tyler Professor of Constitutional Law Laurence H. Tribe '62, who called Bok's decision "very disappointing,"said that the recent tenure decisions againstThayer Lecturer on Law Daniel Tarullo, AssistantProfessor Clare Dalton, and Trubek--all consideredaffiliates of the CLS school-were ideologicallymotivated.

"Anyone who believes that [those decisions] area coincidence has more faith in the neutrality ofthe tenure process than I can muster," said Tribe,who is a nationally--prominent expert on theConstitution.

"I think that Harvard has decided to establisha higher standard of scrutiny for those on theleft, which raises it above what is applied forthose on the right," Trubek said yesterday,shortly after being informed of the decision.

"I am disappointed in Harvard, and I amconvinced they have made a mistake," said Trubek,who plans to return to Wisconsin to teach nextyear.

Bok's unprecedented action may have influencethe case of Dalton, who was denied tenure thisspring. Dalton said yesterday that she has askedBok to reverse the decision to deny her tenure onthe basis of the president's two-year-old memo.

That memo detailed two possible scenarios inwhich Bok would intervene in a Law School tenurecase. The first would be if Vorenberg or otherfaculty members said that tenure had been blockedfor political reasons, as Dalton has claimed. Thesecond would be if the minority who opposed anappointment said that it had been approved becauseof political reasons, which was the standardapplied in the Trubek case.