The regulatory concept of “unfair or deceptive acts or practices” is hardly a new one.

The Federal Trade Commission Act, enacted in 1914, used similar language to empower the eponymous agency it created to protect consumers and businesses. That standard, known as UDAP, was more recently applied to the Consumer Financial Protection Bureau when the CFPB was created by the Dodd-Frank Act in 2010—and it is causing financial firms all sorts of trouble.