Miami Police Chief Bernard Gormeyer said last night on WGBH-TV's show, "The Advocates," that it is the duty of a policeman to invade an individual's privacy in order to prevent an act of violence.

Gormeyer's testimony was used by William Rusher '48, publisher of the National Review, as he sought to show why police should be permitted to keep intelligence records on political dissidents.

"The Advocates" is modeled on a courtroom debate, with two opposing lawyers, witnesses testifying for either side, a judge and an audience which votes as a jury.

Howard Miller, a lawyer opposing Rusher, challenged the police activities on a moral and legal basis, presenting testimony from Ralph Stein, formerly at the U.S. Army Intelligence "New Left Desk" and Caxton Foster, a professor of computer technology at the University of Massachusetts.

Stein said that even such factors as sexual habits, reading tastes, and personal associations are included in the files. Foster said that the computer-based program could eventually be developed to cover virtually all activities of every U.S. citizen.

Rusher's argument stressed that surveillance has been an effective tool in combatting a rising wave of violence. He said that there was little difference between the filing of fingerprints and the filing of intelligence files.

Chief Gormeyer, the star witness in Rusher's case, said that surveillance had helped deter acts of violence, such as a plot to blow up President Nixon's home in Key Biscayne, Fla.

Rusher, who described himself as "a poor man's Bill Buckley," had trouble responding to Miller's questioning of the use and control of such information.