The Supreme Court ruled against the White House today in a case involving the president’s power to make recess appointments when Congress is not in session. Though this power is a regular subject of contention between the president and Congress, this was the first time the Court had ever ruled on the subject.

This is just one skirmish in the ongoing war over the president’s powers. But it could have serious implications for the ability of this or future Congresses to throw sand in the gears of governing.

The real significance of this development is that it makes it possible for the Senate — or, depending on the circumstances, a minority of the Senate — to stop almost any presidential nominee lawmakers don’t like. If these kinds of conflicts came up over only truly controversial nominees, then that wouldn’t be such a bad thing. The problem is that Republicans have decided that if there are agencies they don’t like, they can simply paralyze them by refusing to confirm any of the president’s appointees.

The issue came to a head because Republicans in the Senate have been unusually aggressive in denying President Obama his chosen appointees to executive branch positions. This case concerned the National Labor Relations Board, which has five members, traditionally three from the president’s party and two from the opposition’s party. But Republicans refused to confirm President Obama’s nominees, leaving the NLRB without the quorum it needed to make decisions. During a time when the Senate was conducting pro forma sessions (gaveling into session and then immediately gaveling out) every three days, specifically to avoid going into recess so that Obama could make recess appointments, the administration made the appointments anyway, declaring that the Senate was in recess for all intents and purposes.

In their ruling, the Court said that three days isn’t enough to qualify as a recess, and for a recess to be real (and therefore allow for recess appointments), it has to be at least 10 days long. The ruling makes it much easier for the Senate to use pro forma sessions to thwart the president’s ability to make recess appointments.

It’s important to remember that for the moment, the issue is moot, because the Senate changed its rules to allow administration officials to be confirmed with a majority vote, instead of a filibuster-proof 60-vote majority. (Democrats made this change because just as Republicans decided when Barack Obama became president that they’d filibuster almost every bill, they also decided to filibuster most nominees.) But if Republicans take back the Senate after November’s elections, they could decide not to confirm any of this president’s nominees (whether they change back the rule on the majority required for confirmations or not).

If we’re talking about agency jobs, the president can appoint an acting director or secretary to fill a vacancy, and the place will still function. But in the case of boards like the NLRB, they could be all but shut down. Ian Millhiser explains the implication:

The fullest impact of this decision, however, will likely be felt in 2018. That’s when the five year terms of the NLRB’s current slate of members expire. If an anti-union president controls the White House in 2018, they will be able to effectively invalidate labor protections that have existed since the Franklin Roosevelt Administration by refusing to nominate anyone to this Board. But even if the president supports allowing federal labor law to function in 2018, they will be unable to keep the NLRB functioning if a majority of the Senate is determined to shut down federal labor protections. That is the most important impact of Noel Canning. It means that every five years the Senate will have the unilateral authority to turn off decades of protections for American workers.

Republicans are claiming that the ruling is a vindication of their belief that Barack Obama is a tyrant — and that it bodes well for John Boehner’s lawsuit against the President. But this was a case in which both sides went farther in their dispute than their predecessors had before — Republicans with their blanket refusal to confirm large groups of nominees, and Obama in his assertion that he could make recess appointments during the pro forma sessions. Whether in the future this decision results in paralyzed government and the kind of nullification of laws that Millhiser predicts will be up to the opposition in the Senate, and just how radical they decide to be in their fight against the president. And if the conduct of current Republicans are any indication, it could get ugly.