JUST over a year ago, while most of his colleagues were home for the holidays, a lone senator entered the Capitol and banged the gavel twice. With the first knock he called the empty Senate to order; with the second he quickly adjourned it. Though no work was done, the exercise was repeated every few days. This is what the dull work of obstruction looks like. By forcing the Senate to call "pro forma" sessions, Republicans hoped to prevent Barack Obama from appointing a handful of contentious candidates to important posts. All high-level nominees must be approved by the Senate, unless the body has recessed, in which case a "recess appointment" can be made that lasts up to two years. Senator Obama watched the Democrats block George W. Bush's nominees in just this way. But President Obama rather liked being able to appoint who he chose when he chose. So last January he decided that despite the gavel-banging the Senate had in fact recessed, and he was therefore free to appoint three members to the National Labour Relations Board (NLRB) and a director of the Consumer Financial Protection Bureau (CFPB), both controversial components of the president's regulatory regime. At the time Republicans called it a cynical power grab, and on January 25th a three-judge panel of a federal appeals court agreed. If the president can decide when the Senate was in recess, then he can make appointments when the chamber is at lunch or when he is merely displeased with its inertia, reasoned the judges. The Senate should not be cut out of the confirmation process so easily. The panel went further, noting that the Founding Fathers referred to "the recess," not "a recess," when circumscribing the president's powers. It therefore decided that the only time a president could install his nominees without Senate approval was during the break in between formal sessions of Congress, which usually occurs once a year. Two of the three judges further ruled that only vacancies arising during this time could be filled in this way. The specific case overturned a decision by the NLRB, which would not have had a quorum without the recess appointments. But it calls into question all of the NLRB and CFPB's work from the past year, not to mention hundreds of recess appointments made by previous presidents during Senate breaks. A similar challenge to the CFPB is now winding through the judicial system - but a graver one, because the body was vested with greater powers by the same questionable method. The issue seems destined for the Supreme Court. Although Mr Obama is seen to have overstepped, his supporters claim he was pushed. A bevy of the president's nominees await action in the Democrat-controlled Senate, where Republicans have used the filibuster to prevent up-or-down votes on the candidates. On January 24th the body approved small changes to the procedure, which allows a stubborn minority to block measures not supported by 60 of 100 senators. But supermajorities are still needed to get most work done, meaning that Republicans can continue to frustrate a chastened president.