Let’s go over blue slips one more time.

On February 26, the Senate confirmed the nomination of Eric Miller to the U.S. Court of Appeals for the Ninth Circuit. After nearly a decade in the Justice Department during the George W. Bush and Barack Obama administrations, Miller had become a partner in the law firm of Perkins Coie in Seattle, chairing the firm’s nationwide appellate practice. He had argued 16 cases before the Supreme Court.

The wrinkle was that Washington’s two senators, Patty Murray and Maria Cantwell, did not support Miller. Democrats cried foul, with Senator Amy Klobuchar claiming that this was the first time the Senate had confirmed an appeals-court nominee who did not have the support of both home-state senators. She even tied this to the way America’s founders themselves had designed the Senate to operate.

The Senate has a tradition, going back to 1917 (not to the birth of the republic), of highlighting the views of the senators from the state in which a judicial nominee would serve. It’s called the “blue slip” courtesy because the Judiciary Committee chairman seeks the home-state senators’ position on a blue slip of paper.

The Constitution does not require that any special attention be paid to the views of any particular senators. Neither do Senate or Judiciary Committee rules. That’s why this is best described as a “tradition” or a “courtesy.” The facts of how it has been implemented cannot be in dispute.

Seventeen of the previous 19 Judiciary Committee chairman — seven Democrats and ten Republicans — have used the blue-slip courtesy for its intended purpose, that is, for input. Only two used it as a veto, refusing to give a hearing to nominees without the expressed support of both home-state senators. When a blue slip was simply withheld, as Murray and Cantwell did with Miller, chairmen from Ted Kennedy to Strom Thurmond proceeded as if the home-state senators supported the nominee.