The Supreme Court of the United States Tuesday released a decision in United States v. Washington. The case concerns important issues regarding worker’s rights, the supremacy clause, and mootness.

The case revolves around a 2018 Washington state worker’s compensation law which applied to certain federal workers performing cleanup at the Hanford nuclear site. Hanford was once used by the federal government as a development site for nuclear weapons but began leaked radiation into the atmosphere and surrounding area after its decommission and became one of the most contaminated nuclear areas in US history. The federal government began a monumental cleanup effort in the early 2000s.

Many workers involved in the cleanup experience an increased risk of developing certain rare illnesses. The 2018 Washington law was intended to ensure easier access to worker’s compensation for federal contract workers. The state law declared that all federal contract workers involved in the cleanup were entitled to workers’ compensation should they develop a rare illness as a result of working at the site. The law was upheld by a district court, which ruled that a Congressional waiver allowed the state law to impact federal government conduct. The Supreme Court disagreed, resulting in a unanimous decision from the court declaring the state law to be unconstitutional under the Supremacy Clause.

A major concern for the court was the increased cost to the federal government the law created. By applying to federal contract workers, the state law essentially created a enitrely new category of workers entitled to payment from the federal government. The court stated this law was unequal and imposed “upon the Federal Government costs that state or private entities do not bear. The law consequently violates the Supremacy Clause.”

The case also concerned the issue of mootness. After litigation on this case began, the state of Washington changed its law to apply to all workers at the site in what might have been an attempt to avoid judicial review. However, the court declared that the issue wasn’t moot, declaring “…a case is not moot unless it is impossible for the Court to grant any effectual relief.” The court stated that it held the power to prevent the federal government from having to pay millions of dollars in workers compensation claims, thus rendering the case active.

Washington may set new precedent for the definitions of mootness and supremacy for future litigation.