Federal power
According to legal scholar Bernard Schwartz, Fuller's most noteworthy decision was his 1895 opinion in Pollock v. Farmers' Loan & Trust Co. In 1894, Congress passed the Wilson–Gorman Tariff Act, which contained a rider that levied a two-percent tax on incomes exceeding $4,000 a year. Since it imposed the nation's first peacetime income tax, this provision was deeply controversial, provoking acrimonious debate along geographic, societal, and political lines. Its challengers took the tax to court, where they argued that it was a direct tax that had not been apportioned evenly among the states, in violation of a provision of the Constitution. (In practice, apportioning income tax by state would be impossible, so a ruling on this basis would doom federal income taxes.) When the matter reached the Supreme Court, it unexpectedly agreed with the challengers and, by a 5–4 vote, struck down the income tax. The majority opinion, written by Fuller, held that the Framers intended the term "direct tax" to include property and that income was itself a form of property. Fuller thus ruled the entire act to be unconstitutional. The decision provoked withering criticism from each of the four dissenters, including a paroxysm of ire by Justice John Marshall Harlan that one scholar characterized as "one of the most spectacular displays ever staged by a member of the Court". Harlan wrote that the decision "strikes at the very foundation of national authority", while Justice Henry Billings Brown opined it "approaches the proportion of a national calamity". Each dissenter decried the majority's perceived infidelity to precedent.
The Pollock decision was distinctly unpopular. Much of the public questioned whether Fuller's constitutional analysis was truly in good faith: many felt that the Court was more committed to protecting the wealthy than to following any particular legal philosophy. Former Oregon governor Sylvester Pennoyer even called for the impeachment of the justices in the majority. While the public outcry soon waned, support for a federal income tax grew substantially in subsequent years. The Sixteenth Amendment to the U.S. Constitution, ratified in 1913, abrogated Pollock by allowing Congress to levy income taxes without apportionment; it marked only the third time in American history that a Supreme Court decision was reversed via constitutional amendment. However, the Supreme Court has never formally overruled Pollock's reasoning; to the contrary, Chief Justice John Roberts cited it in the 2012 Affordable Care Act case National Federation of Independent Business v. Sebelius. Law professor Erik M. Jensen noted in 2014 that most legal academics agree that Pollock was "obviously dead wrong"; scholar Calvin H. Johnson called the decision "a terrible example of judicial bad behavior" that should be "reverse[d] in full". Jensen takes a minority position, agreeing with Pollock and extending it to argue for the unconstitutionality of flat taxes and wealth taxes. In any event, Fuller's Pollock opinion remains relevant in contemporary public policy.
Fuller was suspicious of attempts to assert broad federal power over interstate commerce. Questions about the scope of Congress's Commerce Clause authority commonly arose in the context of the Sherman Act, a major 1890 federal antitrust law. In the first such case, United States v. E. C. Knight Co. (1895), Fuller led the Court in limiting the federal government's powers. The Department of Justice had filed suit under the Sherman Act against the American Sugar Refining Company, arguing that it was a monopoly because it controlled over ninety percent of the American sugar refining market. Writing for an eight-justice majority, Fuller concluded Congress could not proscribe such monopolies because they only implicated manufacturing and thus did not fall under the Commerce Clause. Stating that "[c]ommerce succeeds to manufacture and is not a part of it," he maintained that the sugar-refining trust had no direct impact on interstate commerce. Fuller feared that a broader interpretation of the Commerce Clause would impinge upon states' rights, and he thus held the Sugar Trust could only be broken up by the states in which it operated. The case displays Fuller's tendency to support a limited federal government. The legal academy generally views Knight as an unduly restrictive interpretation of the Commerce Clause, although legal scholar Richard Epstein has argued that it aligns with founding-era precedents. The Court's expansive Commerce Clause decisions during the New Deal period essentially abrogated Knight.
Fuller participated in several other major antitrust cases. In the 1904 case of Northern Securities Co. v. United States, a majority broke up the Northern Securities Company, a railroad holding company, believing it to be a monopoly. Fuller dissented, joining opinions written by Justices Edward Douglass White and Oliver Wendell Holmes Jr. The dissenters argued that simply holding stock in a company did not count as interstate commerce, and so they would have held that the Sherman Act did not apply to holding companies. The justices were unanimous in Swift & Co. v. United States (1905), which gave the Court's blessing to antitrust enforcement against meat-packing companies. Although meat-packing did not directly involve interstate commerce, the Court held that the Commerce Clause still applied because the meat products would eventually be sold across state lines. Citing Swift and other cases, legal historian James W. Ely has argued that Fuller was not opposed to federal antitrust laws per se, but only to expansive readings of the Commerce Clause. In another antitrust case, Loewe v. Lawlor (1908), Fuller wrote for a unanimous Court that labor unions were subject to the Sherman Act. The ruling was commonly thought to evince antipathy toward organized labor. Its broad interpretation of the antitrust laws appeared difficult to reconcile with Knight, and law professor David P. Currie wrote that the apparent contradiction "suggests that [Fuller] may not have been guided exclusively by neutral legal principles".
Fuller's attempts to limit the national government's power did not always meet with the support of his fellow justices. He dissented from the Court's 1903 decision in Champion v. Ames, in which five justices upheld a federal ban on transporting lottery tickets across state lines. In his opinion, Fuller demurred that the majority's reasoning gave Congress "the absolute and exclusive power to prohibit the transportation of anything or anybody from one state to another. He feared that the law violated the principles of federalism and states' rights protected by the Tenth Amendment. The ruling in Ames was among the first to grant the federal government a de facto police power to protect the welfare of the public. It proved a historically significant step toward expanding congressional authority, and legal scholar John Semonche wrote that by resisting it, Fuller "sought to put his finger in the dike". The chief justice also dissented in McCray v. United States, a 1904 case that approved the use of the federal taxing power for regulatory purposes. McCray effectively allowed Congress to regulate intrastate commercial activity by simply levying taxes on it; the decision curtailed Fuller's opinion in Knight and showed his support for federalism could not always garner the support of a majority of the Court.
