Last Thursday, Sen. Dick Durbin invited Chief Justice John Roberts to testify before the Senate Judiciary Committee about, well, to put it directly—the Supreme Court’s diaphanous ethics regime. On Tuesday evening, in his letter to Durbin in which he declined the invitation, Roberts finally named the problem: “Testimony before the Senate Judiciary Committee by the Chief Justice of the United States is exceedingly rare, as one might expect in light of separation of powers concerns and the importance of preserving judicial independence,” he wrote. In other words, the justices can enforce checks and balances on the other branches, but the other branches can enforce no checks or balances upon the justices. Which is precisely the problem the Senate Judiciary Committee is attempting to solve.