Baltimore decriminalized cannabis possession in October 2014, downgrading anything less than 10 grams to a citation, and anything under 50 pounds to a misdemeanor. In 2017, Brandon Soderberg and Ethan McLeod, two Baltimore-based journalists, acquired data from Baltimore Police about the enforcement of these laws in the intervening years. I analyzed this data and found that the number of misdemeanor marijuana possession arrests in a given area correlated strongly with the percentage of its population which is black, even when controlling for income.
Ethan and Brandon wrote an in-depth story in Baltimore Fishbowl around my analysis, including a lot of history, validation through other data sources, and quotes from people on both sides of the story (including the police). It ran on December 28th, 2018.
On January 29th, 2019, Baltimore States Attorney Marilyn Mosby announced her office would no longer prosecute marijuana possession charges, and would seek to throw out thousands of these convictions dating back to 2011. A white paper released in conjunction with the announcement cited our resarch in explaining the rationale for the decision.