THE INSIDIOUS USE of judicial nominees as political pawns continued Tuesday with a Republican filibuster of Caitlin J. Halligan.

Voted well-qualified by a unanimous American Bar Association, Ms. Halligan was tapped by President Obama to fill a long-vacant seat on the U.S. Court of Appeals for the D.C. Circuit. She is general counsel for the New York County District Attorney’s Office in Manhattan and has served ably in public posts and private practice; she earned the enthusiastic support of a bipartisan group of legal luminaries, including Miguel A. Estrada, whom President Bush nominated to the D.C. Circuit.

Those who have worked with Ms. Halligan say she is a skilled lawyer with moderate views — a depiction that is at odds with the distorted portrait of her painted by Republicans.

GOP lawmakers accused Ms. Halligan of being an anti-gun extremist. Why? In 2003, as New York solicitor general, she represented the state in appellate courts when gun manufacturers challenged a suit brought by then-Attorney General Eliot Spitzer. The state ultimately lost, but it was Mr. Spitzer, not Ms. Halligan, who made the decision to pursue this route. Lawmakers – many of whom hold law degrees – should know better than to ascribe the views of clients to their attorneys.

Others argued that the D.C. Circuit’s diminished caseload did not warrant filling the vacancy; Republicans rightly scoffed at such a ploy when used by Democrats to block GOP appointees.

What happened to the Bush-era bipartisan “Gang of 14” and its pledge to reserve filibusters for those “extraordinary circumstances” in which a nominee’s qualifications or ethics are suspect or her views far outside the mainstream? On Tuesday, four Republicans from that “gang” — John McCain (Ariz.), Lindsey O. Graham (S.C.), and Olympia Snowe and Susan Collins of Maine — abandoned that worthy agreement.

Ms. Halligan’s nomination was blocked for two reasons: to keep a Democratic appointee from joining a bench that is considered a farm team for the Supreme Court; and to avenge the defeat of eminently qualified Republican nominees such as Mr. Estrada. It is a disgrace to the party that Lisa Murkowski of Alaska was the only Republican to endorse an up-or-down vote.