The Mayo Foundation for Medical Education and Research v. United States case in 2010 revolved around the issue of whether medical residents should be considered students, and thus exempt from Social Security taxes under federal law. The Internal Revenue Service (IRS) had issued a rule stating that full-time employees, which it defined as those working at least 40 hours per week, could not be classified as students. The Mayo Foundation challenged this rule arguing that their medical residents were indeed students because they were engaged in a structured educational program with significant studying and exams involved. However, the Supreme Court ruled unanimously against the Mayo Foundation holding that the IRS's interpretation was reasonable given its expertise on tax matters and therefore deserved deference by courts under Chevron U.S.A., Inc v Natural Resources Defense Council standard.

In the dissenting opinion for Mayo Foundation v. United States, Justice Roberts disagreed with the majority's decision to uphold a Treasury Department regulation that categorizes medical residents as employees rather than students for tax purposes. He argued that this interpretation was inconsistent with Congress' intent when it enacted an exemption from Social Security taxes for students working at their schools "as part of their education." According to him, medical residents fit within this category because they work long hours in hospitals as part of their rigorous educational programs and are not merely employed by those institutions. Therefore, he believed they should be exempted from paying these taxes under federal law. Furthermore, he criticized the Court's deference to administrative agencies in interpreting ambiguous statutes and suggested that such deference undermines judicial independence.