Boris Volfson of Huntington, Indiana recently received U.S. Patent 6,960,975 for his design of an antigravity space vehicle. Some people might consider patents on unworkable products to be relatively harmless. Others worry that these patents can be used to defraud investors. Mistakes in the U.S. Patent Office are unfortunate, but inevitable. Some 5,000 examiners handle 350,000 applications per year.