Paul Freund, Carl M. Loeb University Professor and leading expert on constitutional law, said yesterday that President Nixon is "probably not" obligated to hand over White House papers to the Senate committee investigating Watergate.

However, Freund stressed that "the issue is in another dimension" in which Nixon is under a political and moral obligation to cooperate with the Senate committee. Nixon refused to testify in Saturday's letter to Senator Sam J. Ervin (D-N.C.), the committee's chairman.

Freund said that the present investigation entails an "unusual situation," and that Nixon's legal position appears to be supported by existing Federal statutes pertaining to executive privileges regarding intra-departmental government papers.

He noted that despite Nixon's legal position, the primary consideration is that this administration is behaving as it did during the Vietnam War, ignoring moral considerations in favor of legal ones.

Harold Berman, professor of Law, said that "from the viewpoint of constitutional law, the [Nixon's Saturday] statement is justified, but ultimately we'd like to know everything he knows."

Andrew Kaufman, professor of Law, said that the situation is unique because it is not a matter of policy but one of "personal wrongdoing."

He noted that the case is different from previous ones including President Truman's refusal in 1953 to appear before the McCarthy Committee, a case cited by Nixon on Saturday. But in searching for precedents, Kaufman explained, "if you find something vaguely alike, you use it."

He added that a practical issue is involved. If every presidential message becomes grounds for compelling presidential testimony, the operations of government would be impaired, Kaufman explained. If the issue of personal wrong-doing is ignored, he said, "there's a lot to be said for both sides."

Kaufmann said he believes that the American public should wait to hear the rest of the testimony. Referring to the grounds for impeachment and how they've been interpreted to-date, he said, "'High crimes and misdemeanors' has a sense to it."

Although the Supreme Court has traditionally not interfered with the other two branches of government or relationships between them, Kaufman cited the Court, reversal of the House ruling that unseated Adam Clayton Powell (D-N.Y.) as an indication that the Court might play some role in defining relevent Constitutional questions.

"It wouldn't be constitutionally inappropriate to show up before the Congressional Committee if he [Nixon] wanted to," he said