The Tenth Justice by Brad Meltzer

Supreme Court clerk Ben Addison and co-clerk Lisa are fresh out of law school and anxious to make it good in their field. When Ben accidentally discloses court information he finds himself in hot water. Wanting to "fix" things, Ben, his friends, and Lisa use their power to catch the "rat", they only get into deeper trouble. Meltzer's first novel was a great start to his career and is still a good read fourteen years later.