A narrow ruling by Mexico's Supreme Court could eventually clear a path to make recreational use of marijuana legal.
Four people in the Mexican Society for Responsible and Tolerant Personal Use will now be permitted to grow and smoke their own marijuana.
Marijuana still cannot be sold in Mexico but some say the court's ruling could lead to full legalisation.
Mexico has long struggled with violent conflict from drug cartels.
The advocacy group first brought the case forward in 2013, seeking permission to grow plants for recreational use.
The court voted 4-1 that prohibiting people from growing the drug for consumption was unconstitutional.