(CNN)Here's a look at Supreme Court nominations.
Under Article II of the Constitution, the President nominates justices to the Supreme Court, with the "advice and consent of the Senate."
If a vacancy occurs when Congress is not in session, a recess appointment allows an appointee to serve without Senate approval until Congress reconvenes.
One hundred and sixty-four nominations have been officially submitted to the Senate (including nominations for chief justice). Of those, there have been 127 confirmations, with seven instances of individuals declining to serve.
The American Bar Association's Standing Committee on the Federal Judiciary evaluates nominees to the Supreme Court for the Justice Department and the Senate Judiciary Committee. The organization has three possible rankings: qualified, well-qualified, and not qualified.
There is no requirement that the chief justice of the Supreme Court previously serve as an associate justice, but five of the 17 chief justices have. Three justices served on the Court immediately before being elevated to chief justice: Edward D. White, Harlan Fiske Stone and William Rehnquist. Two justices had a break between their service as associate justice and being appointed chief justice: Charles Evans Hughes and John Rutledge.
Franklin D. Roosevelt appointed nine justices during his 12-year presidency, the most since George Washington. Jimmy Carter is the only president to complete a full term of office and never have the opportunity to nominate a Supreme Court justice.
1952 - Presidents begin consulting the American Bar Association before making Supreme Court nominations.
1950s - President Dwight D. Eisenhower makes recess appointments of Earl Warren, Potter Stewart and William J. Brennan. All three are later confirmed by the Senate.
1955 - Nominees begin appearing before the Senate Judiciary Committee for confirmation hearings.
1981 - Senate Judiciary Committee hearings are televised for the first time.
1987 - President Ronald Reagan nominates Robert Bork for a seat but he is rejected by the Senate. Anthony Kennedy takes the seat.
July 1, 1991 - President George H.W. Bush nominates Clarence Thomas to succeed Justice Thurgood Marshall, who is retiring.
October 11, 1991 - Anita Hill testifies on Capitol Hill, accusing Thomas of sexual harassment in the workplace. Thomas denies the allegations.
October 15, 1991 - Thomas wins Senate confirmation by the narrowest margin in the 20th century, 52-48.
1990s - President Bill Clinton is the first Democratic president since 1967 to fill a Supreme Court vacancy. He appoints two: Justice Stephen Breyer and Justice Ruth Bader Ginsburg
September 5, 2005 - President George W. Bush nominates John Roberts to succeed the late William Rehnquist as chief justice.
September 29, 2005 - Roberts is confirmed by the Senate (78-22).
October 3, 2005 - Roberts is sworn in. The same day, Bush nominates Harriet Miers to succeed Justice Sandra Day O'Connor, who is retiring.
October 27, 2005 - Miers withdraws her nomination.
October 31, 2005 - Bush nominates Samuel Alito.
January 31, 2006 - Alito is confirmed by the Senate (58-42). He is sworn in by Roberts.
May 26, 2009 - President Barack Obama nominates Sonia Sotomayor to succeed Justice David Souter, who is retiring.
August 8, 2009 - Sotomayor is sworn in as the first Hispanic justice on the Supreme Court.
August 5, 2010 - Kagan is confirmed by the Senate (63-37).
August 7, 2010 - Kagan is sworn in.
March 16, 2016 - Obama nominates Merrick Garland to replace the late Justice Antonin Scalia. No hearings are held.
April 7, 2017 - The Senate confirms Gorsuch (54-45).
April 10, 2017 - Gorsuch is sworn in.
July 10, 2018 - Trump nominates Brett Kavanaugh to fill the seat of Justice Kennedy, who is retiring.
October 6, 2018 - Kavanaugh wins Senate confirmation by the narrowest margin in 137 years, in a 50-48 vote. In 1881, Stanley Matthews was confirmed by the Senate in a 24-23 vote. The ceremonial swearing-in event takes place at the White House on October 8.
September 29, 2020 - Trump nominates Amy Coney Barrett, a conservative federal appeals court judge, to succeed the late Justice Ginsburg.