Corruption is an unparalleled threat to democracy and prosperity that costs the global economy as much as $2 trillion a year, and it will require the approach of a marathon rather than a sprint to eradicate the scourge, according to William Brownfield, the U.S. assistant secretary of state for international narcotics and law enforcement. Victories like the current transformation of Ukrainian traffic police from reviled bribe takers to respected public servants give citizens the kind of hope needed to fortify them through the long, tough process of reform.