Owen Roberts' key vote came in March 1937 in West Coast Hotel Co. v. Parrish. The year before, the Supreme Court had overturned the state of New York's minimum-wage law, with Roberts voting with the conservative majority. But in Parrish, Roberts and therefore the court essentially reversed themselves by upholding a minimum-wage law for women in the state of Washington.
After the Parrish decision, FDR's New Deal legislation enjoyed clear legal sailing, as Jeff Shesol has pointed out in Supreme Power: Franklin Roosevelt vs. the Supreme Court. By the end of its 1937 term, the court had given a green light to the National Labor Relations and Social Security Acts.
What changed Roberts' thinking in the period between two nearly identical minimum-wage cases? It was impossible to know at the time. He did not write a separate opinion in the Parrish case. Even FDR's attorney general, Homer Cummings, was puzzled by the new Roberts.
What was dramatically different by March 1937 was the Roosevelt administration's willingness to take on the Supreme Court. A month earlier, Roosevelt had announced a plan to tame the judiciary. He wanted the authority, with the advice and consent of the Senate, to add a new judge to the Supreme Court and other federal courts for every judge who reached 10 years of service and the age of 70 but did not retire.
Roberts cannot be accused of caving in because of Roosevelt's court-packing plan: He cast his official vote in the Parrish case in December 1936, months before FDR announced his plan (and months before the Parrish decision was made public). But in the fall of 1936, Roosevelt had won a landslide election to a second term, and the popularity of the New Deal was readily apparent. Few could have failed to anticipate the public outcry that would have ensued if the Supreme Court continued to declare New Deal legislation unconstitutional. And Roberts was close to the politically astute chief justice, Charles Evans Hughes, who had nearly defeated Woodrow Wilson in the 1916 presidential election.
Roberts did write a three-page memo defending his Parrish decision, published posthumously in 1955. But during his time on the court, his vote went unexplained. It was viewed both as good for the New Deal and as a blow to FDR's court-packing plan, which lost steam once the court upheld key New Deal legislation.
Unlike Owen Roberts, John Roberts made an effort to explain his key vote immediately. He insisted that the penalty the Affordable Care Act imposes on those who refuse to buy health insurance is really a tax.
John Roberts' explanation, however, is no clearer than Owen Roberts' non-explanation. As angry conservatives have noted, it defies common sense and the explicit intent of the Affordable Care Act. In the words of Justice Antonin Scalia, "To say that the individual mandate merely imposes a tax is not to interpret the statute but to rewrite it."
What John Roberts has done for the moment, nonetheless, is to relieve the Supreme Court of the charge that it is essentially an extension of the conservative wing of the Republican Party — much as Owen Roberts did in the middle of the Great Depression.
For the chief justice's new liberal fans, however, there is still much to worry about. Roberts is not their ally, and his reading of the Commerce Clause is as narrow as that of the Supreme Court's other conservatives. As Justice Ruth Bader Ginsburg wrote scathingly of Roberts' analysis, "This rigid reading of the clause makes scant sense and is stunningly regressive."
Roosevelt knew Owen Roberts was not a justice he could rely on. "It would be a little naive to refuse to recognize some connection between these 1937 decisions and the Supreme Court fight" over his packing plan, he later wrote. Only after the court's four conservative justices began to retire could FDR count on it to uphold the New Deal.
President Obama is in a similar position today. Only a fifth liberal justice can guarantee him the legislative freedom he will need.
Nicolaus Mills is a professor of American studies at Sarah Lawrence College and the author of "The Triumph of Meanness: America's War Against Its Better Self."