The Democratic-led Senate on Thursday voted to confirm Judge Sonia Sotomayor as the first Hispanic justice on the Supreme Court.
The vote was 68 to 31 largely along party lines.
Sotomayor, a federal judge for 17 years, replaces Justice David Souter and is not expected to affect the ideological balance of the court, since Souter was also a liberal-leaning judge.
But conservatives remain concerned and unconvinced that the 55-year-old judge would apply the law with blind justice.
"The evidence tells us that Judge Sotomayor lacks a proper understanding of the role of judges and the judiciary in our constitutional system," Family Research Council president Tony Perkins said in a statement. "Sadly, rather than honoring the clear text of the Constitution, the record shows her to be a judicial activist who has no qualms about imposing her policy preferences from the bench, rather than interpreting the law as written."
When President Barack Obama announced his nominee to the nation's highest court in May, Perkins criticized the president for choosing someone with "a compelling personal story over a judicial pick with a solid constitutional judicial philosophy."
"A compelling personal story is no substitute for allegiance to the Constitution and its sound application to public life," Perkins said.
Sotomayor grew up in a Bronx housing project after her parents left Puerto Rico. Her father, a manual laborer, died when she was 9, leaving her mother to raise two children on her own while juggling two jobs.
The confirmation of the first woman of color to the high court has drawn applause from civil rights groups and Democrats, who have noted that Sotomayor brings more federal judicial experience to the Supreme Court than anyone confirmed for the Court in the past 70 years.
Conservatives, meanwhile, hope to see impartiality from the new justice.
"We hope that as a Supreme Court Justice she will refrain from writing new laws from the bench and demonstrate respect for the text and history of the Constitution," said Perkins.
Sotomayor will serve as the 111th justice.