WASHINGTON (AP) _ The Supreme Court today agreed to decide whether federal agencies are required to bargain with the unions representing their employees over subjects the unions raise during the life of a contract agreement.

The justices said they will resolve conflicting appeals court rulings over agencies' obligation to negotiate such ``midterm'' proposals initiated by the unions.

In the cases granted review today, the 4th U.S. Circuit Court of Appeals ruled that the Interior Department's U.S. Geological Survey was not legally bound to bargain over such a proposal raised by the union representing its employees in Reston, Va.

The Federal Service Labor-Management Relations Statute governs employment relations for federal employees. Under the law, the Federal Labor Relations Authority is responsible for resolving unfair-labor-practice complaints and other labor disputes _ the same role played by the National Labor Relations Board for private industry.

While negotiating a collective bargaining agreement with the Geological Survey, Local 1309 of the National Federation of Federal Employees proposed being given a contractual right to have the agency negotiate ``matters not covered by the provisions of this agreement.''

The agency refused to negotiate over the proposal, prompting the union to file an unfair-labor-practice complaint with the FLRA.

The authority ruled against the Geological Survey, but on appeal the 4th Circuit court reversed the authority's decision. The appeals court concluded that union-initiated bargaining during the term of a collective bargaining agreement is contrary to the federal labor-management law.

The FLRA and the union then appealed to the Supreme Court, arguing that the 4th Circuit court's ruling conflicts with one issued by the U.S. Court of Appeals for the District of Columbia.

Justice Department lawyers, representing the Geological Survey, urged the highest court to reject the appeals. They said the conflict ``does not have enough practical significance to warrant this court's review.''

The cases are National Federation of Federal Employees vs. Department of Interior, 97-1184, and FLRA vs. Department of Interior, 97-1243.