“I am stunned,” declares Justice Samuel Alito, dissenting in the Supreme Court’s ruling against President Trump over spending foreign aid. It could signal tougher than expected sledding in Mr. Trump’s campaign against federal waste, and comes as senators are asserting a role in decisions to cut spending. The high court’s move paves the way for the release of $2 billion in already authorized aid, a reminder of the limits of Mr. Trump’s attempt to reform by decree.