JAMES TARANTO: Nuclear Fallout: Democrats filibuster an Obama nominee.

The 47-52 procedural vote that blocked the nomination of Debo Adegbile as assistant attorney general for civil rights was actually bipartisan, with “no” votes coming from all 44 Republicans who were present. But because of a recent Senate rule change, pushed through by Majority Leader Harry Reid, the GOP can’t block a nominee without Democratic help.

It was in November that Reid and the Democrats invoked the so-called nuclear option, depriving the Republicans of their ability to block nominations on what is called a cloture vote–a vote to end debate and bring the nomination to the floor. Before the change, it took 60 “yes” votes to invoke cloture, so that a unified minority party with at least 41 seats could prevent nominations from coming to the floor. Democrats have held the majority throughout Obama’s presidency, but they’ve been below the 60-vote threshold for most of that time. Under the new practice, a simple majority is enough to break a filibuster, so that cloture is tantamount to confirmation.

That means that if the Democratic majority stays unified (or has few enough defections–currently five–to leave a majority in support), it can confirm any Obama nominee. The flip side, as we noted in November, is that one day Senate Democrats will find themselves in the minority, unable to block a Republican president’s nominees. But a smaller unintended consequence came into view yesterday. As the Hill’s Meredith Shiner notes, an effect of the majority rule is “squarely putting the burden of confirmation on the majority and politically exposing the most vulnerable members of that majority.”

Oft evil will shall evil mar.