More than 140 federal judgeships are currently unoccupied, a record high number. President Trump has nominated almost 60 candidates to fill those slots but so far only seven have been confirmed.

There are many reasons why the Senate has not been able to confirm more of President Trump’s nominees, but a major obstacle has been Democrat abuse of a Senate Judiciary Committee practice more commonly known as the “blue slip.”

When a candidate is nominated to a federal judicial vacancy, the two senators from the states of that vacancy are given blue slips of paper by the Senate Judiciary Committee chairman soliciting the senators’ opinion of the nominee in question.

The written opinions of the home-state senators are then taken into consideration when the Judiciary Committee considers the nomination. But sometimes senators choose not to return the blue slip at all, thus delaying and sometimes even blocking a nomination entirely.

Senate Democrats are currently refusing to return blue slips on a number of President Trump nominees and when the possibility of proceeding to committee consideration without the blue slips has been raised, these same Democrats have claimed Republicans are trying to destroy one of the Senate’s most sacred traditions.

Nothing could be further from the truth.

The blue slip was invented in 1917—128 years after the First Congress convened. It was never treated as a veto until 1955, when Senator James Eastland became Chairman of this Committee. Eastland was an ardent segregationist and, by turning the blue slip into a veto, he was trying to block the implementation of Brown v. Board of Education.

Eastland’s successor, Senator Ted Kennedy, immediately changed the status of the blue slip when he became chairman. To make a long story short, since 1955, there have been eight chairmen of the Committee, including Eastland. By my count, two have treated the blue slip as a veto. The remaining six either said the blue slip was not a veto or did not treat the blue slip as if it were a veto. So the practice, even since 1955, is mixed. And of course those first 128 years of the Republic also count.

The blue slip has taken on added importance because, in 2013, the Democrats eliminated the filibuster from the executive calendar. We should be cognizant that when we change the rules—the actual, written protections we can rely on—we are left reliant on customs. Customs can always be changed, especially when they are not particularly strong customs.

That’s something I hope we all consider as we move forward and determine how to process pending nominees.