On any given day in the United States, at least 137,000 people sit behind bars on simple drug-possession charges, according to a report released by the American Civil Liberties Union and Human Rights Watch. Nearly two-thirds of them are in local jails. The report says that most of these jailed inmates have not been convicted of any crime: They're sitting in a cell, awaiting a day in court, an appearance that may be months or even years off, because they can't afford to post bail.