to use the administrative procedures act in the law to strike down an agency decision. essentially, what the court decided was that the cdc as an agency within the executive branch, the executive branch does not make law. that s congress that makes law. and the agency only has the power that congress gives it in the statute. and the court concluded that the agency in this case exceeded that explicit authority. by essentially ruling that, well, does this count as sanitation requiring people to wear masks? and the court s interpretation of that word really hinged on that word sanitation, whether or not sanitation means to clean or to prevent other things from getting dirty. it s a very sort of complicated analysis that you can see another court concluding differently. but at least for now, the interpretation is that the mask mandate exceeded cdc s authority under the animating statute.