THE PHILADELPHIA Police Department's new interview and interrogation policy - a copy of which was obtained by the Daily News - lays out numerous rules.

Although many of the stipulations were already in practice, they had not officially been part of a written policy.

Some of the rules include:

* Witnesses, crime victims and even potential suspects who are brought in by police for "noncustodial, nonaccusatory" questioning are to be told that they can stop and leave at any time.

* Detectives need approval from a supervisor to question a suspect for more than 12 hours if criminal charges aren't filed, and no suspect can be held for more than 36 hours.

* Detailed logs must show when interviews begin and end, and note that detectives advised individuals being questioned that they were free to leave when they wanted.

* Supervisors are required to check on the well-being of people being interviewed by police at least once during their shift.

* Investigators are prohibited from using physical force of any kind, or making threats of any kind, including deportation, against a potential suspect or against the person's relatives.

* A suspect can invoke his Miranda rights - and immediately end any interrogation - by presenting a letter from an attorney stating that he can't be questioned without the attorney present.

* Photos of a potential suspect must be shown to a victim or witness one at a time - rather than in a collage - and cannot be shown by a detective working the case.

* Authorized interpreters must conduct interviews of victims or witnesses who don't speak or fully understand English.