In June 2012, the US Supreme Court seemingly ended the political battle over the ACA’s legitimacy when it upheld core tenets of the legislation. Writing for the majority, Chief Justice John Roberts endorsed the government’s right to enforce ACA’s “individual mandate” that required persons above certain income levels to purchase health care or face tax penalties. The Court thus sanctioned what might be considered fiscal principles of herd immunity—namely, that networks of health care and social support work best when most people participate in them.3
