Some time ago, we wrote about how the Fed and the ECB’s governance and communication were converging. Our focus was on the policy, governance and communications framework, including the 2% inflation objective, the voting rotation, post-meeting press conference, prompt publication of meeting minutes, and the like.

But important differences are built into the legal design of these two systems. Perhaps the most important one is the contrasting roles of the regional Federal Reserve Banks and that of the National Central Banks (NCBs)...