It's the biggest secret in a city known for not keeping them. The nine Supreme Court justices and more than three dozen other people have kept quiet for more than two months about how the high court is going to rule on the constitutionality of President Barack Obama's health care overhaul. This is information that could move markets, turn economies and greatly affect this fall's national elections, including the presidential contest between Obama and Republican challenger Mitt Romney. But unlike the Congress and the executive branch, which seem to leak information willy-nilly, the Supreme Court, from the chief justice down to the lowliest clerk, appears to truly value silence when it comes to upcoming court opinions, big and small.