Aging but enormously powerful and politically divided, the U.S. Supreme Court controls many aspects of life in America.

The death Saturday of Justice Antonin Scalia, a strident conservative appointed three decades ago by then-president Ronald Reagan, not only opens a seat on the nine-member bench but also launches a political war in an election year.

Democratic President Barack Obama, in the final year of his mandate, has the right to nominate a replacement, but his choice must be confirmed by the Republican-dominated Senate. The announcement of Scalia's death immediately launched a loud, bitter battle over his replacement.

Here are some facts about the U.S. Supreme Court:

  • Four Republican-appointed justices sit on the court against four Democratic-appointed ones.
  • The appointment process is highly politicized:

"We ought to make the 2016 election a referendum on the Supreme Court," U.S. senator and Republican presidential contender Ted Cruz said Sunday on NBC's Meet the Press

"The president can decide whatever he wants, but I'm just telling you the Senate is not moving forward on it until we have a new president, and I agree with that," Sen. Marco Rubio, one of Cruz's campaign opponents, said on CBS's Face the Nation.

  • Not since Richard Nixon has a U.S. president had the opportunity to appoint more than two judges. Nixon appointed four and Obama has appointed two already during his time in office. 

  • Democrats in the Senate rejected the appointment of Robert Bork in the election season of 1988 and that has politicized the confirmation process ever since. The lead Democrat on the committee at that time was Joe Biden, now Obama's vice president.

  • Justice Anthony Kennedy was appointed by Ronald Reagan on Feb. 18, 1988, about the same time before a presidential election that Republicans now say is too close for Obama to appoint Scalia's replacement.

  • The current court will continue to hear cases with or without a replacement, including a major case involving abortion rights.
  • Three justices are over the age of 75; Ruth Bader Ginsburg and Stephen Breyer, who are liberals, and Anthony Kennedy, a conservative. Chances are all three will leave the bench one way or another over the course of the next presidency, especially if it runs two terms. If that is the case, the majority on the court — whether conservative or liberal — would be locked in for a couple of generations, past the middle of the century, as justices serve for life.

With files from Reuters