Sometimes it seems nothing ever changes in Washington, and then suddenly change comes so fast it makes your head spin.

Case in point: For decades, the U.S. Court of Appeals for the D.C. Circuit had been dominated by judges appointed by Republican presidents. Considered the U.S.'s most important court after the Supreme Court, the D.C. Circuit's balance of power remained lopsided -- broadly in favor of business and against costly regulation -- even under President Barack Obama because Senate Republicans used the filibuster to prevent his selections from being confirmed.

The opening created when John Roberts left the court in 2005 to become chief justice of the Supreme Court, for example, went unfilled for eight years. Indeed, Obama is the only president since 1948, when the circuit court system was established, not to have a judge confirmed to the D.C. Circuit during his first term.

All that changed in the last three days as a result of the filibuster-rule changes the Senate approved in November. The D.C. Circuit's balance of power is now 6-4 in Democrats' favor with the confirmation of two female nominees. Early today, after an all-night debate, the Senate confirmed Georgetown University law professor Nina Pillard to the D.C. Circuit, having done the same for Washington lawyer Patricia Millett on Tuesday. A third Obama choice, U.S. District Judge Robert Wilkins, could soon join them, making the balance of power 7-4.

Keep an eye on Millett and Pillard, both of whom are experienced Supreme Court advocates. Pillard drafted the government's brief in U.S. v. Virginia, in which she successfully argued that Virginia Military Institute must admit women. She also has championed the rights of men, having successfully represented a Nevada state employee who was fired for taking unpaid paternity leave.

The additions represent a sea change for the court -- one whose repercussions will be felt most especially in the regulatory arena. The court hears most appeals from federal agencies, has exclusive jurisdiction over certain national security issues, and decides many constitutional challenges involving executive-branch powers.

Among the issues that could be affected: challenges to Dodd-Frank regulations, including the just-announced Volcker rule, which limits proprietary trading by banks.

The addition of three Obama judges could make a difference on an existing challenge to the Federal Communications Commission's net-neutrality rule, which bans Internet providers from discriminating against customers. Verizon Communications Inc. claims the FCC doesn't have the authority to impose net neutrality.

Other landmark cases that could land on the court's doorstep involve the Environmental Protection Agency's carbon-emissions rules and labor regulations.

Changes in the court's makeup were made possible thanks to the events of Nov. 21, when Harry Reid, using his power as Senate majority leader, allowed a simple majority vote to change long-standing filibuster rules. Now, executive-branch nominees and judgeships -- with the exception of Supreme Court nominees -- can win confirmation with just 51 votes, down from the 60 previously needed to cut off debate. (Republicans still have the power to talk for hours and use other tactics to delay votes on nominees.)

The result has been a confirmation spree. In recent days, the Senate has confirmed Representative Mel Watt to head the Federal Housing Finance Agency, where he could have a major effect on U.S. housing policy as the overseer of Fannie Mae and Freddie Mac, and Chai Rachel Feldblum to the Equal Employment Opportunity Commission.

Reid is expected to hold votes on other important nominees this week and next, including Janet Yellen to be Federal Reserve chairman, Jeh Johnson as secretary of the Department of Homeland Security, John Koskinen as commissioner of the Internal Revenue Service and two other federal judges.

Until this week, Obama's nominees to the D.C. Circuit had gone nowhere as Republicans claimed the court's caseload wasn't heavy enough to justify the salaries. The caseload for the court's seven judges, meanwhile, rocketed to 188 this year, from 119 in 2006, according to Patricia Wald, who served on the court from 1979 to 1999.

It would be a mistake, though, to expect radical changes in jurisprudence overnight. Like most federal appeals courts, the D.C. Circuit hears cases in panels of three randomly selected judges. The court also draws on a pool of six senior judges, five of whom were selected by Republican presidents. They carry a reduced caseload, yet their opinions are influential when they do participate.

(Paula Dwyer is a member of the Bloomberg View editorial board. Follow her on Twitter.)