Legal maneuvering began in Montgomery County Circuit Court yesterday to determine where Robert Daly Angell, the convicted murderer of two county policemen, will serve his prison term.

The alternatives are the forbidding 200-year-old state penitentiary in Baltimore or the more modern Patuxent Institution, which is supposed to provide psychiatric aid designed to rehabilitate inmates.

A report by Patuxent Institution officials recently recommended that Angell be classified a "defective delinquent," which could enable the 20-year-old confessed murderer of three persons to serve an indeterminate sentence at the Jessup facility. He was sentenced to three consecutive life terms in September.

Montgomery County Circuit Court Judge John J. Mitchell recommended at that time that Angell not be considered for parole, even after he becomes eligible in 40 years.

Yesterday, Mitchell agreed to a request by the State's Attorney's Office that Angell go through a jury trial in July to determine whether or not he does meet the legal standards of defective delinquency.

However, as both Deputy State's Attorney Timothy E. Clarke and defense attorney J. James McKenna pointed out yesterday, legislation now pending in Annapolis would substantially change the requirements for commitment to Patuxent and the procedures for such commitment.

The legislation, which is considered almost certain to pass this month, eliminates the requirement for a jury trial or judicial determination that an inmate is a defective delinquent. Thus the question of a trial for Angell in July would become moot.

The legislation also changes the standards by which an inmate is judged an appropriate subject for Patuxent, and eliminates the term "defective delinquent," substituting "eligible person" instead.

If the legislation is passed, as expected, Angell would have to be examined all over again by the doctors and officials of Patuxent, who would use the new standards - which emphasize the questions of emotional stability and the possibility of improved chances for rehabilitation at Patuxent - to determine whether or not he is eligible to serve his term there.

Deputy State's Attorney Clarke said yesterday that he has not yet decided whether he will oppose the moves to have Angell committed to Patuxent, which, like the Baltimore penitentiary, is a maximum security prison. "I'm keeping my options open," Clarke said yesterday.