The U.S. Court of Appeals for the District of Columbia Circuit ruled recently that a workplace rule that barred employees who were witnesses in an internal misconduct investigation from discussing the investigation with other employees violated federal labor law.

In so ruling, the appeals court affirmed in part a decision issued by the National Labor Relations Board (NLRB) in the case of Hyundai America Shipping Agency, Inc. v. NLRB, 805 F.3d 309 (D.C. Cir. 2015).

The NLRB during the Obama Administration has attempted to expand the scope of the National Labor Relations Act (NLRA) beyond traditional union-management issues to other areas, including mandatory arbitration agreements, employee off-work social media use, and employer work rules.

The ruling in Hyundai by the influential D.C. Circuit is significant because it largely endorses a troubling Board interpretation of the NLRA, and is likely to increase the legal risk to employers who place a premium on confidentiality of workplace investigations.

The rule invalidated in Hyundai is similar to the rule that the NLRB invalidated earlier this year in Banner Health, a case that itself is currently on appeal to the D.C. Circuit.

A copy of the D.C. Circuit’s decision in Hyundai is available online here.