Putting Senate Republicans on the spot, Barack Obama has chosen a respected moderate to fill Antonin Scalia’s Supreme Court seat. Merrick Garland’s résumé looks central-casting perfect: two Harvard degrees, clerking for Justice William Brennan and serving as a federal prosecutor in the Oklahoma City bombing trial. Now he is chief judge on the “DC circuit” court of appeals, America’s second-most influential tribunal, where he has served since 1997. At 63, Mr Garland is the oldest nominee in nearly half a century. He is no liberal firebrand, but the Republicans are sticking to their guns and refusing to hold confirmation hearings. Mitch McConnell, the Senate majority leader, says it’s “about a principle, not a person”; voters “should have a say” in filling the vacancy, so the Senate should hold off until the next president takes office. If Donald Trump continues his march toward the Republican nomination, that tune may change.