Usually when Congress cancels a committee meeting the country misses nothing more than grandstanding. But this week the Senate Judiciary Committee had to halt progress on confirming talented judges thanks to GOP Senator Jeff Flake of Arizona.

The committee was scheduled to meet Thursday to move some 20 judicial nominees. But Mr. Flake has said he will block all judicial nominees until he receives a vote on a bill that would insulate Robert Mueller’s Russia investigation from normal political accountability. The GOP’s one-seat...