In the case of Department of the Treasury, Internal Revenue Service v. Federal Labor Relations Authority et al., 1989, the U.S. Supreme Court ruled that federal agencies are not required to negotiate with labor unions over matters of employee rights and working conditions if those issues are already addressed by federal law or government-wide regulations. The court's decision was based on an interpretation of a provision in the Federal Service Labor-Management Relations Statute which states that collective bargaining does not extend to matters covered by federal statute. This ruling clarified that while unions have a right to bargain collectively under this statute, their ability to do so is limited when it comes to topics already governed by existing laws or regulations.

In the dissenting opinion for the case Department of Treasury, Internal Revenue Service v. Federal Labor Relations Authority et al., Justice Antonin Scalia disagreed with the majority's interpretation of Section 7117(a)(1) of Title VII. He argued that this section does not grant a union the right to negotiate over matters concerning conditions of employment if they are already covered by federal law or government-wide regulations. Instead, he believed it only prevents agencies from refusing to bargain over such issues when there is no applicable law or regulation in place. Furthermore, he contended that even if an agency has discretion under a statute or regulation, it doesn't mean they have an obligation to negotiate how that discretion should be exercised unless specifically required by Congress. In his view, allowing unions to demand negotiations on these discretionary decisions would disrupt efficient governmental operations and undermine managerial authority.