In June 2004, Highton joined the Supreme Court. She was the first woman to join the Court (under a democratic government), although Carmen Argibay's appointment had been announced earlier. When it came to Senate approval, 51 of the senators present voted for her appointment and five were against. In August 2005 she was appointed vice-president of the Court.
The International Association of Women Judges (IAWJ) awarded her Human Rights Award during a conference held in Seoul on 18 May 2010.
Highton and her husband Alberto Mario Nolasco have two sons.