A few weeks before the 2016 election, Brett Kavanaugh, then a judge on the United States Court of Appeals for the D.C. Circuit, drew a lot of attention with a ruling concluding that the structure of the Consumer Financial Protection Bureau, conceived in the wake of the 2008 financial crisis, was unconstitutional. The agency, in the judge’s view, was simply too powerful, and Congress erred when making its director independent of, and unaccountable to, the president of the United States. That design, as conceived by lawmakers, served the purpose of insulating the CFPB from undue political influence — say, from...