Congress has passed a law specific to Medicare, requiring that the government provide the public with advance notice and the opportunity to comment on any “rule, requirement, or other statement of policy” that “establishes or changes a substantive legal standard governing . . . the payment of services.” 42 U.S.C. §1395hh(a)(2). In 2014, the government posted on its website a new policy that, according to the Court, “dramatically—and retroactively—reduced payments to hospitals serving low-income patients,” and without the opportunity for notice-and-comment. Allina Health Services and other hospitals that provided care to low-income Medicare patients in 2012 challenged the government’s failure to follow its notice-and-comment obligations. The District Court found for the government, but the D.C. Circuit reversed and found for the hospitals. Today, the Court affirmed, holding that the government had failed to advance any argument as to why it could evade its statutory notice-and-comment obligations when establishing or changing the “gap”-filling policy at issue here.