Though it's human to err, admitting it doesn't come as naturally to the species - much less hiring someone to ferret out our mistakes. But that's exactly what the best government agencies do, setting up inspectors general, internal affairs departments, and the like to review and reconsider their work.
Philadelphia District Attorney Seth Williams deserves credit for his newly announced plan to correct some of his office's mistakes, which can have the serious consequences of putting innocent people in jail and letting guilty people go unpunished.
Williams this week announced the creation of a unit dedicated to investigating wrongful convictions, to be headed by Assistant District Attorney Mark Gilson, a veteran homicide prosecutor. One of Gilson's best-known prosecutions, for the 2000 murder of seven people in a crack house, was hampered by a wrongful arrest before it was successfully tried.