California voters approve Proposition 64, legalizing adult-use cannabis in the most populous U.S. state

On November 8, 2016—almost twenty years to the day after legalizing medical marijuana under Proposition 215—California voters approved Proposition 64 (the Control, Regulate and Tax Adult Use of Marijuana Act, or AUMA) by a decisive margin of 57.13% Yes (7,979,041 votes) to 42.87% No (5,987,020 votes).

What Proposition 64 changed immediately and in 2018

Personal possession and home cultivation became legal the day after the election on November 9, 2016, while licensed commercial retail sales launched on January 1, 2018:

• Possession limits: Adults 21 and older may possess up to 1 ounce (28.5 grams) of cannabis flower and up to 8 grams of concentrated cannabis.
• Home cultivation: Adults may grow up to 6 living cannabis plants per residence indoors (or outdoors where permitted by local ordinance), locked and out of public view.
• Resentencing and record expungement: Unlike earlier state ballot measures, Prop 64 included landmark criminal justice reform allowing people with prior California cannabis convictions that would now be legal or lesser offenses to petition for resentencing, dismissal, or sealing of their records—later automated by California law (AB 1793 in 2018).
• Tax allocation: Prop 64 established a 15% state excise tax on retail sales, directing revenue after regulatory costs toward youth education and substance prevention, environmental restoration of public lands damaged by illicit grows, and community reinvestment grants.

Photo: Adobe Stock. Later contextual stock: Legacy Kush dispensary in Santa Ana, California, November 11, 2023; not a photograph of the 2016 vote.