Elena Kagan has been sworn in as the newest justice in the US Supreme Court.
She is President Barack Obama's second appointment to the US's most powerful court and only the fourth woman to serve on the nine-member panel.
The 50-year-old becomes the youngest serving Supreme Court judge. She will serve alongside President Obama's first appointment, Sonia Sotomayor.
She is thought unlikely to alter the balance of the court as she replaces liberal justice John Paul Stevens.
Ms Kagan swore to "faithfully and impartially" uphold the law for all Americans.
She will formally join the court on 1 October, just before the judges return to the bench for a new session after their summer recess.
She said she would "work my hardest and try my best to fulfil these commitments and serve this country I love".
For the first time in the court's history, three female justices will serve at the same time.
Ms Kagan was confirmed by the Senate in a 63-37 vote on Thursday.
Five Republicans supported President Obama's choice, with Nebraskan Ben Nelson the only Democrat to oppose it.
Critics have said she would advocate for liberal policies, such as gun control and abortion rights, and have criticised her lack of judicial experience.
The nine-member court is the ultimate arbiter of the US constitution, with the power to strike-down laws and set precedent for lower courts.
Because members are appointed for life, their influence can extend far beyond the term of the president who appointed them.
Ms Kagan was a White House aide to President Bill Clinton and later dean of Harvard Law School.
When he took office, Mr Obama named her US solicitor general, the lawyer who argues the government position before the Supreme Court.