Q&A: US Supreme Court
Elena Kagan, President Barack Obama's second pick to the US Supreme Court, has won approval from the Senate Judiciary Committee and is widely expected to win confirmation.
Supreme Court justices serve for life, so Ms Kagan could be on the court for decades and leave a lasting imprint on American life.
She would replace Justice John Paul Stevens, who retired in June.
How are Supreme Court justices appointed?
The constitution gives the president sole authority to appoint Supreme Court justices.
However, any appointment he makes must be approved by a majority vote in the Senate.
Before facing a vote, nominees are called before the Senate Judiciary Committee where they are asked to testify about their judicial philosophy.
Has the Senate ever blocked a president's appointment?
Yes. In 1987, the Democrats (who held a majority in the Senate) voted down President Ronald Reagan's nominee for the Supreme Court, Robert Bork.
The Democratic senators objected to Mr Bork's views on abortion and executive power.
The Senate has rarely used its power to block nominees, however.
What is so important about the Supreme Court?
The Supreme Court is the highest court in the US and has the authority to strike down any state or federal law it deems unconstitutional.
It is regularly called upon to rule on issues of individual freedom - such as civil rights and free speech - and matters like abortion, capital punishment and police ability to detain and search criminal suspects.
These involve basic constitutional principles that the court must apply.
Its landmark cases have shaped modern America, such as Brown v Board of Education in 1954, which signalled the end of legal segregation, Roe v Wade in 1973, which secured the right to abortion, or the 1976 decision allowing states and federal legislators to impose the death penalty.
So the decisions made by the nine justices on the Supreme Court can have a huge impact on American life.
Cases are decided by majority vote of the justices.
How long do justices serve on the Supreme Court?
Once appointed, justices can - if they want to - serve on the court for the rest of their lives.
They are allowed to retire or resign, and can be forced out of office by congressional impeachment.
Potentially, however, and in practice, Supreme Court justices serve on the court for decades.
What is the political make-up of the Supreme Court?
Although their life-tenure gives Supreme Court justices independence from partisan politics, they are appointed (and approved) by politicians, so the Supreme Court is far from being a politics-free zone.
And because their decisions carry so much weight, the political views of the Supreme Court are a subject of much interest and debate.
At present, four of the nine justices can broadly be described as liberal (Stephen Breyer, Ruth Bader Ginsburg, Sonia Sotomayor and John Paul Stevens) and four can be described as conservative (John Roberts, Antonin Scalia, Clarence Thomas and Samuel Alito).
The ninth justice - Anthony Kennedy - is a swing voter, sometimes siding with liberals, sometimes with the conservatives.
Will Justice Stevens's retirement change the political balance of the court?
Unlikely. Although Ms Kagan has never served as a judge, her professional track record suggests she will rule with the liberal bloc, so her nomination is unlikely to change the court's ideological make-up, analysts say.
Some past justices have disappointed the presidents who appointed them and the political activists who fought for their confirmation. For one, Justice David Souter, who retired last year, was appointed by Republican George H W Bush but became a reliable liberal vote.
Unless one of the conservative justices dies or retires, Mr Obama is unlikely to be able to alter the political make-up of the court.