The President's crime commission, directed by James L. Vorenberg, professor of Law, charged in a report Saturday that racial bias of police forces is crippling law enforcement in the United States.

"No lasting improvement is likely unless police-community relations are sub-4stantially improved," the 228 page document concluded. And it laid responsibility for the widespread distrust of police among minority groups squarely on the "many ill-conceived actions of individual police officers and administrators."

The commission said its studies showed that:

* there is extensive oral abuse of minority groups -- about 15 per cent of the street interviews they observed began with a "brusque or nasty" command.

* Policemen pull guns more often than the need to in making arrests.

* Negroes and Puerto Ricans are often arrested for offenses that police would overlook if committed by whites.

Actual physical police brutality is very rare -- found only in isolated sections of the South, according to the commission. It reported only 20 instances of such physical violence in the more than 5000 encounters between police and civilians they observed.

The real problem is one of attitudes -- both of and toward police -- the commis- sion said. It proposed community relations units to reduce distrust and urged police departments to screen prospective officers more carefully and supervise them more strictly.

The commission also reiterated the suggestion to revise police department organization that was the core of its first report issued in February. The new system would establish three levels of police officers, insuring that crime investigators were a special college-trained elite.

A separate section of Saturday's report treated the problem of police corruption. The commission equivocated on the "extent of police dishonesty," but detailed corrupt practices like rolling drunks and accepting bribes from prostitutes. They said the instances of unethical conduct were made more numerous because police departments tend to assign their most incompetent officers to slum areas.

There are more crime commission reports to come -- eight in all are expected by June 30th. Topics will include organized crime, corrections, juvenile delinquency, and drugs.

Vorenberg, who has been on leave all this year, will continue as executive director of the commission until the reports are completed. He plans to teach and study in Europe this summer and will return to Harvard in the fall. Massachusetts Attorney General Elliot L. Richardson has already engaged him to help in a study of criminal justice in the state when he returns