The growing Prince George's County police force is requesting federal funds to acquire its own full-time legal adviser, similar to those in 290 large police forces around the nation.

The county's police department, with 875 officers, has been getting legal advice from busy county and state's attorneys on interpretation of changing laws, defending officers and the department from civil suits, prosecuting officers in internal disciplinary hearings and generally advising officers on the laws they must enforce.

If its application for a $26,000 federal Law Enforcement Assistance Administration grant is appproved, many of these legal duties and numerous others would be handled by an in-house lawyer, on call 24-hours a day to the police department.

It would make the county the third area jurisdiction with a lawyer stationed full time at police headquarters. The District, which has four full-time attorneys to handle almost all legal business for its 4,650-officer force, was one of the nation's first policy forces to hire its own lawyer.

Montgomery County police acquired a full-time legal adviser in 1973 under a similar LEAA grant, which expires this year after being renewed twice by LEAA. Alan Wright, the current legal adviser, said this week he expected Montgomery County will fund his office out of its own budget in the next fiscal year. The county's LEAA grant was for $23,129, augmented by $1,670 from the county and $900 from the state. Montgomery has about 800 officers on its force.

In Prince George's all police legal questions currently are handled by county and state's attorneys, as they are in neighboring Virginia jurisdictions, which have smaller police forces.

The $26,404 grant being requested by Prince George's will "give us a full-time legal adviser in our police department headquarters in Forestville," says John Hoxie, spokesman for the county police department. "It's primarily a question of availability," sayd Hoxie, "county and state's attorneys are extremely busy, constantly involved in litigation and not available as much as we need them for advice and planning."

The new legal adviser would assist the chief of police in reviewing current and proposed police procedures, act as adviser on disciplinary proceedings against officers, review county, state and federal court decisions for changes in the interpretation of laws and review all legislative proposals affect the police.

The proposed post would involve the police lawyer primarily in "preventive" law and not tie him up in numerous court appearances, Hoxie said. The county's office of law will still defend police officers from civil suits and the state's attorney will continue to handle the criminal suits police officers have investigated.

Most of the legal adviser posts have been created at police departments around the country to provide "day to day advice for police chiefs on the growing number of complicated legal problems that face officers on the street and police departments themselves," says Vernon S. Gill, general counsel for the District's police department, D.C.'s legal adviser post was recommended in 1967 by the report of the President's Commission on Crime in the District and funded in 1970. "Ours was the prototype for legal adviser units across the country," Gill said, "and now such units are recommended by the American Bar Association" and many police and legal groups.

Police legal problems have become increasingly complicated in recent years, not only for officers in the street faced with new laws, changing interpretations of existing laws and closer public scratiny of all police practices, but also inside the police station. There has been increasing unioniration of police departments and the new Maryland policemen's bill of rights spells out legal steps that must be taken in any disciplinary proceedings against police officers. Both can put rank and file officers against the police administration.

If the grant proposal is approved the new legal adviser could be in residence by the end of the year.