Supreme Court Justice Samuel Alito was treated for dehydration at a hospital after a previously undisclosed March 20 incident in Philadelphia, sources told Fox News.He was not admitted and returned home the same night without complications.Alito, 76, attended a Federalist Society dinner that evening and reported feeling lightheaded, prompting his security detail to recommend a precautionary hospital visit. Sources said the justice has had no issues since.This is a developing story. Please check back for updates.