Sandra Day O’Connor, the first woman to serve on the US Supreme Court and seen as a crucial swing voter, is to retire leaving the door open for US President George W. Bush to select her successor.
Speculation is already mounting that President Bush will nominate a conservative to replace her in an effort to tilt the balance of opinion on the bench.
O’Connor, 75, has often cast the deciding vote in the nine-member court on contentious issues such as abortion.
Her retirement is the first in 11 years on the ageing Supreme Court. It came as a surprise as the subject of recent retirement rumours had been Chief Justice William Rehnquist.
O’Connor, a former Arizona politician, was nominated by Ronald Reagan to serve on the Supreme Court and took up her seat in 1981.