John J. Coppolella Jr., a disabled laborer, early Tuesday joined the growing number of helpless citizens publicly witnesses as beaten by Philadelphia policemen. His thrashing and manhandling by police took place less than four days after Mayor Frank L. Rizzo told reporters at City Hall that in all cases previously recounted in this newspaper, "I'm sure the police acted properly."

"We have a very, very good Police Department, and they're not brutal," Mr. Rizzo said. "If there's any brutality, it's towards the police."  Specifically referring to the case of William Cradle, who in front of eight witnesses on April 29 was beaten unconscious by five policemen, with more standing by. Mr. Rizzo scoffed:  "It's very easy to break some of those nightsticks."  Two nightsticks were shattered on Mr. Cradle's body.

Every citizen should feel stark horror in the face of systematic illegal behavior by Philadelphia policemen recounted in the continuing articles by Inquirer reporters Jonathan Neumann and William K. Marimow.

Beyond that, the overriding concern is that the violation of basic human rights by policemen is not only systematic, taking place in total safety to the policemen and under the noses of the entire command structure, but that it is being tacitly condoned by the major and his subordinates.

Since the disclosures began, not a single public word of admonition, concern or discipline has been expressed by anyone in the city government. Even decent, humane policemen, who surely constitute the preponderance of the force, must find it difficult to read that response as saying anything other than:  Go forth and do likewise.

To the great credit of the U. S. Justice Department, and especially of U. S. Attorney David Marston and the Federal Bureau of Investigation, a major federal investigation of illegal police behavior is going on under civil rights laws.

Philadelphia suffers from the assumption by many who hold power – and from the fear by many who do not – that the politically powerful are above the reach of the law.

That was the manner in which Herbert Fineman, speaker of the state House of Representatives, operated until he was convicted Friday of obstruction of justice, through the work of the FBI and Mr. Marston's office. It is the manner in which Mr. Rizzo is behaving in implicitly condoning illegal police behavior. It is the assumption on which corruption by many in local government goes on unpunished and unabated.

The principal hope for restitution of basic human rights in Philadelphia and, for combatting systematic corruption lies with the U. S. Department of Justice, and ultimately with President Carter himself. Both are under continuing political pressure to dismiss Mr. Marston, a Republican appointee, and to replace him with a Democrat who is attractive to the very forces who benefit from the breakdown of law and would benefit from cutting off Mr. Marston's hearteningly effective efforts.

The Carter Administration would vitally serve the hopes for human rights and for honest government in Philadelphia by making, and making public, a commitment to keep Mr. Marston in the U. S. Attorney's office for the remaining three years of a full four-year term.