A key weapon in the arsenal of U.S. Attorney Patrick Fitzgerald and his prosecutors in Chicago has been a section of the federal anti-fraud statute that makes it a crime to deprive citizens or corporate shareholders of “honest services.”

It’s been used to convict dozens of state and local government officials, as well as newspaper magnate Conrad Black and former Gov. George Ryan of Illinois. Fitzgerald cited the honest services in the April indictment of another ex-Illinois governor, Rod Blagojevich.