Colorado's 96th supreme court justice took her seat Friday after being sworn in by her father, a retired court of appeals judge.
Monica Marquez replaced Mary Mullarkey on the bench. Mullarkey retired on Nov. 30.
The new justice, 41, is a former deputy attorney general.
She becomes the second Latino justice on the current supreme court, the first Latina ever to sit on the court, Colorado's first openly gay justice, and the third openly gay state supreme court justice in the country.
Marquez's father, Jose D.L. Marquez, administered her oath of office. The elder Marquez also made history as Colorado's first Latino court of appeals judge.
He retired from the state bench in 2008 after 20 years of service.