Historically, many Supreme Court nominations made in a President’s final year in office are rejected by the Senate. That started with John Quincy Adams and last occurred to Lyndon B. Johnson.

It is critically important that the Senate hold pro forma sessions, since President Barack Obama would be able to make a recess appointment to the Supreme Court if the Senate goes out of session. Currently, there is a five-day recess this week and a two-week recess scheduled for April. There have been twelve such recess appointments to the high court. A recess appointment would last until the end of the Senate’s next session.

Historically, most presidents select a nominee within a week of a Supreme Court vacancy. However, there have been several lengthy vacancies when the Senate refused to play ball with controversial presidents or controversial nominees.

President John Tyler had a particularly difficult time filling vacancies. Smith Thompson died in office December 18, 1843. His replacement, Samuel Nelson, was in office starting February 14, 1845. That’s a vacancy of 424 days. Henry Baldwin died in office April 21, 1844. His replacement, Robert Cooper, was in office starting August 4, 1846. This vacancy lasted 835 days because Tyler could not get the Senate to work with him. During Tyler’s presidency, the Senate rejected nine separate Supreme Court nominations!

Most recently, Abe Fortas resigned May 14, 1969. His replacement, Harry Blackmun, was in office starting June 9, 1970, making the gap just longer than a year.

Several pending cases were expected to be 5-4 decisions. Crucially, the immigration (DAPA) case, United States v. Texas et al., and the mandatory union dues case, Friedrichs v. California Teachers Association, and the Little Sisters of the Poor Home for the Aged v. Burwell cases on the contraception mandate accommodation.

Decisions that are tied with a 4-4 vote have no binding precedent and the decision of the lower court is upheld. This would be good in United States v. Texas et al., because the lower court’s decision was that states have standing to sue against an Obama policy that muzzles states from enforcing immigration laws. But this would bad in the Friedrichs case as the lower court ruled that teachers must pay union dues, even if those dues fund political causes that violate a union members beliefs. Likewise, if the lower court’s decision in the Little Sisters of the Poor case were to be upheld, it would force the nonprofit organization to fund contraception, even though that violates their religious beliefs.