The union of the city's prison guards, after losing a court attempt this week to prevent the layoffs of 225 correctional employes, has resorted to a new tactic in its campaign against the city -- federal arbitration.

American Federation of Government Employees vice president Donald MacIntyre said yesterday that while the union can no longer stop the layoffs completely, it does hope at least to delay the layoffs through an arbitration procedure, by invoking a union contract clause that he says requires union-city negotiations before contract changes, including layoffs, can be made.

The process leading to the call for arbitration actually began on May 6, when the union filed a grievance against the D.C. Corrections Department. The grievance had been held on a back burner until two recent and seemingly contradictory court rulings left the union, one official said, with "few other choices.

On June 23, U.S. District Court Judge june L. Green, acting in a lawsuit brought by inmates in the maximum security facility at D.C.'s Lorton Reformatory, ordered the corrections department to place an additional 30 officers there to ensure what Green called a minimum level of safety.

In a four-page order citing the inmates' constitutional rights to freedom from cruel and unusual punishment, Green said the city must present to the court by July 10 a timetable for deployment of the expanded guard force and implementation of new security measures within the violence-plagued facility.

But eight days later, on Tuesday of this week, D.C. Superior Court Judge William E. Stewart ruled against a union-sponsored suit that asked the court to block the city's proposed reduction in force, paying the way for the layoffs of 150 correctional officers and 75 other employes at Lorton and the D.C. jail.

Although the union maintained that the layoffs would jeopardize the officers' safety and cause an increase in violence at both facilities, Stewart ruled against them.

"It is not the function of the court to establish guidelines," Stewart said, adding that he was not in a position to tell the corrections department how many officers it should have in its facilities.

Following this setback, union officials fell back on the May 6 grievance procedures, arguing that both their contract and the 1980 District Personnel Act give them the right to bargain with management about layoffs procedures. The union has asked the Federal Mediation and Conciliation Service to arbitrate the grievance.

AFGE vice president MacIntyre maintains the union is entitled to some say. "If we're not in a position to prevent the reduction in force," he said, "we are in a position to minimize the adverse impact on the work force, to identify other jobs they could go into [and] to give them the opportunity to be retrained . . .

"We might have lost a few battles in the courts," Macintyre said, "but I think that, through arbitration, we will win the war." m