The Senate Judiciary Committee held a confirmation hearing yesterday on the nomination of Robert H. Bork to the prestigious U.S. Court of Appeals here. During the course of the hearing, Bork told senators present of his views on obedience to decisions of the U.S. Supreme Court and his concern about judicial activism, which he called "imperialism."

But it was Bork as the former solicitor general during the Nixon administration who captured the restless crowd in the committee hearing room when he explained, once again, why he fired Watergate special prosecutor Archibald Cox in 1973 in what became known as the "Saturday Night Massacre."

There was a "moral issue" involved for then attorney general Elliott L. Richardson and his deputy, William D. Ruckelshaus, both of whom resigned rather than carry out Nixon's order that Cox be dismissed, Bork explained. Richardson had promised the Senate and others that he would not fire Cox, and Ruckleshaus, who was brought to the Department of Justice by Richardson, felt that he, too, was bound by those promises, Bork said.

Bork, third in line in the Justice Department hierarchy, became acting attorney general when Richardson and Ruckleshaus resigned. He was left with what he described yesterday as the "symbolic confrontation" between the special prosecutor and Nixon, who was determined to fire him.

"There was nobody after me, nobody," Bork said.

There would have been mass resignations at the Justice Department if he left too, Bork said, and so he carried out the job to "preserve the ongoing effectiveness" of the department. There was a "personal fear of the consequences," Bork said yesterday, but "I could not let that affect my decision."

The committee probably will vote today on the nomination, while the Senate is expected to take it up soon afterward.