Pro-life groups applauded a rare move by the U.S. Senate to block abortion advocate Caitlin Halligan from the D.C. Circuit Court of Appeals.

"A judge should be an impartial arbiter of the facts" rather than push for what he or she thinks is "social progress," the Family Research Council said on Dec. 6.

Nathanael Bennett, director of government affairs for the American Center for Law and Justice, added that Halligan's record could not "withstand the rigorous examination that is typically required of nominees to the D.C. Circuit Court."

Halligan, whose appointment by President Barack Obama was narrowly approved by the Senate Judiciary Committee in March, clerked for Supreme Court Justice Stephen Breyer and served as New York state's solicitor general from 2001 to 2007.

She currently serves as general counsel at the New York County District Attorney's Office.

Senate Republicans filibustered the Dec. 6 vote that would have ended debate and led to a vote on Halligan's actual nomination. The Senate vote was 54-45—six votes short of the 60 necessary to proceed.

Filibusters in similar situations are known to be rare. In 2005, a bipartisan group of senators crafted an agreement to avoid filibustering judicial nominations except in "extraordinary" circumstances.

Republican lawmakers argued that Halligan would be an activist judge and was too extreme to approve.

Sen. Charles Grassley (R-Iowa), ranking minority member of the Judiciary Committee, criticized Halligan at her confirmation hearing for her "record of advocating extreme liberal positions on constitutional issues."

Several pro-life groups had also opposed the nomination, arguing that Halligan was radical in her abortion advocacy and that appointing her to a lifetime position on a high federal court would have disastrous results for the nation.

"Her brand of judicial activism would be a devastating blow in the D.C. Circuit Court, which plays a major role in interpreting federal statutes and regulations," the Family Research Council warned on the day before the vote.

The D.C. Circuit Court of Appeals is considered by legal experts to be one of the most powerful courts in the nation, second only to the U.S. Supreme Court.

Several judges from the D.C. Circuit Court have gone on to be appointed to the Supreme Court, including current Chief Justice John G. Roberts Jr.