Why do most people get arrested in New York City? For possession of small amounts of marijuana.

According to The Drug Policy Alliance, which got its figures from the New York Division of Criminal Justice Services, 50,383 people were arrested for marijuana possession in 2010, or nearly 140 people a day — an increase of 69 percent since 2005.

The Alliance said the rise in arrests last year was not related to a rise in use, citing federal data that show marijuana use peaked around 1980. The number of marijuana arrests in New York City has risen for six years in a row, and now accounts for 15% of all arrests there. 

Minorities are disproportionately affected: blacks and Latinos made up 86 percent of the arrests, even though, the Alliance said, “research consistently shows that young whites use marijuana at higher rates.”

Individuals carrying small amounts of marijuana who emptied it from their bags or pockets on a police stop risked arrest because they had exposed the marijuana to “public view,” the Alliance said. In 1977, the New York state legislature decriminalized possession of 25 grams or less of marijuana; first-time offenders faced only a $100 fine, not arrest. Individuals could be arrested, however, for burning marijuana or having it “open to public view.”