In the case of Mitchell, Secretary of Labor v. King Packing Co., 1955, the U.S. Supreme Court ruled in favor of the Secretary of Labor. The issue at hand was whether or not time spent by meatpackers sharpening their knives during work hours should be considered as part of their regular working hours under the Fair Labor Standards Act (FLSA). The court held that since knife-sharpening is an integral and indispensable part to performing productive work for which workers are employed, it must be counted as work time subject to FLSA provisions. This decision set a precedent for considering preparatory activities essential to primary tasks as compensable working time.

In the dissenting opinion for Mitchell v. King Packing Co., Justice Frankfurter disagreed with the majority's interpretation of "waiting time" under the Fair Labor Standards Act (FLSA). He argued that, according to Department of Labor regulations and previous court rulings, waiting time should be considered compensable work hours if it is spent predominantly for the employer’s benefit. In this case, he believed that meatpackers' knife-sharpening activities were integral and indispensable to their principal activities; therefore, they should be compensated for this time. The justice also expressed concern about potential negative impacts on workers’ rights due to a narrow interpretation of FLSA provisions by courts or employers.