Congress specifically delegates to the Secretary of the Treasury the legislative authority to write tax regulations. However, the Secretary may fail to prescribe regulations despite a statutory order. Such spurning of regulatory duties raises questions about the extent to which a Code section is operative without the required regulations and how a stand-alone section should be interpreted in the absence of its regulations. In Francisco v. Commissioner, the Tax Court majority held that American Samoan income could be excluded under section 931(a) despite the Secretary’s failure to issue congressionally-mandated regulations that define what constitutes section 931(a) excludable income. The Tax Court relied on the plain language of section 931, closely related non-Code provisions, and expressions of congressional intent contained in legislative history to render the section 931(a) exclusion operative in the absence of its required regulations. It concluded that, to the extent income was earned from the performance of personal services in international waters by an American Samoan resident, it was neither American Samoan source income nor effectively connected to American Samoa, thus making the taxpayer ineligible for the section 931(a) exclusion.This Note assesses the Tax Court’s decision to give life to section 931(a) despite its non-existent regulations. Part I explains the process of taxing U.S. citizens in American Samoa and highlights the facts and arguments made in Francisco. Part II describes the Tax Court’s opinion and explains how the court utilized other provisions of the Code and other treasury regulations in the absence of regulations. Part III critiques the court’s willingness to apply its own income-sourcing rules in the absence of regulations interpreting section 931(a), and argues that the court incorrectly made a judgment that Congress left to the Secretary. Part III also argues that under the rules used by the court, the taxpayer’s income could have been sourced in American Samoa and therefore eligible for the section 931(a) exclusion.