In the case of Charles Dowd Box Co., Inc. v. Courtney et al., 1961, the U.S Supreme Court ruled that federal courts have jurisdiction over labor disputes involving unfair labor practices even if a state court has already issued an injunction in such cases. The dispute arose when Charles Dowd Box Company sought to prevent its employees from striking and picketing by obtaining an injunction from a Massachusetts state court. However, the union argued that this was an unfair labor practice under federal law and brought their case before the National Labor Relations Board (NLRB). While proceedings were ongoing at NLRB, the company asked for enforcement of its state-court injunction which led to contempt charges against union officials who had ignored it. The Supreme Court held that Congress intended for jurisdiction over these matters to lie with federal authorities as per national policy set out in Federal Labor Management Relations Act (also known as Taft-Hartley Act), thus overriding any conflicting decisions made by states' courts. This decision reinforced supremacy of federal laws over state laws in areas where Congress has acted decisively.

In the dissenting opinion for Charles Dowd Box Co., Inc. v. Courtney et al., Justice Frankfurter disagreed with the majority's interpretation of Section 301(a) of the Labor Management Relations Act, arguing that it did not grant federal courts jurisdiction over suits by unions to enforce collective bargaining agreements against employers. He contended that Congress intended this section to be a limited grant of jurisdiction, only allowing federal courts to hear cases involving violations of contracts between an employer and labor organization representing employees in industries affecting commerce. The language used in Section 301(a), he argued, was too narrow to include suits brought by unions on behalf of their members as opposed to those directly between employers and labor organizations themselves. Furthermore, he believed that expanding federal court jurisdiction would undermine state authority over contract law disputes which traditionally fell within their purview.