What Is Proposition 64 in California?

September 21, 2026 | Nafiz M. Ahmed

California voters approved Proposition 64 in November 2016, making it one of the earliest states to legalize recreational marijuana. Officially called the Adult Use of Marijuana Act, the measure removed most criminal penalties tied to personal cannabis use for adults 21 and older. Licensed retail sales followed about a year later, beginning in January 2018.

While Prop 64 opened the door for legal recreational use, it did not make everything about marijuana legal. There are still rules about how much you can possess and where, as well as what happens if you get behind the wheel after using it. Violating any of these rules can still result in criminal charges. Read on for the key details you should know.

What Proposition 64 Changed

Before Prop 64 passed, recreational marijuana use was illegal in California. Medical marijuana had been permitted since 1996, but anyone using cannabis outside of that framework faced potential criminal charges.

Proposition 64 changed the landscape in several significant ways:

Adults 21 and older can now legally possess up to 28.5 grams of cannabis flower and up to 8 grams of concentrated cannabis.
Individuals can grow up to six plants inside their home for personal use.
A licensing framework was created for commercial cannabis growers and retailers.
A 15% state excise tax now applies to retail cannabis sales. California’s separate cultivation tax ended in 2022.
Many former marijuana-related felonies were retroactively reduced to misdemeanors, and people convicted under the old laws gained the right to petition for resentencing.

That last provision has been very impactful. Thousands of Californians have used the resentencing process to reduce old convictions that no longer reflect the state’s current stance on cannabis. If you have a prior marijuana conviction on your record, you may still be eligible to petition the court for relief.

What Is Still Illegal Under Prop 64?

Legalization came with guardrails. Not every form of marijuana use is permitted, and some of the restrictions carry serious criminal consequences. For example:

Consuming marijuana in any public space can result in a $100 fine.
Providing cannabis to anyone under 21 is prohibited.
Possessing more than the legal limits without a commercial license remains a criminal offense.
Using marijuana on federal property is still illegal regardless of state law.

Marijuana also remains a Schedule I controlled substance under federal law. While federal enforcement against individual users in legal states has been rare, the conflict between state and federal law has not been fully resolved.

Marijuana DUI Charges in California

The restriction that tends to catch people off guard is driving. Operating a vehicle under the influence of marijuana is a criminal offense under California Vehicle Code Section 23152(f), and Prop 64 did nothing to change that.

Unlike alcohol, there is no set legal limit for THC in the bloodstream in the context of a marijuana DUI. Law enforcement relies on field sobriety tests and behavioral observations to assess impairment instead. If an officer suspects cannabis impairment, they may also request a blood test. Refusing that test can lead to an automatic license suspension.

The penalties for a first-time marijuana DUI conviction can include:

Fines and court fees
A mandatory DUI education program
Probation and a suspended driver’s license
Up to six months in county jail

Repeat offenses and DUI cases involving injury can carry significantly harsher consequences.

Call Ahmed & Sukaram, Criminal Defense Attorneys To Schedule a Confidential Consultation With a San Jose Drug Crimes Attorney

Proposition 64 gave California adults broad freedom to use marijuana legally, but the line between legal use and a criminal charge can be thinner than many people realize. If you’re facing charges, setting up a confidential consultation with a San Jose drug crimes lawyer is one of the best steps you can take.

For more information, please contact our criminal defense law firm of Ahmed & Sukaram, Criminal Defense Attorneys at the nearest location for a consultation.

Ahmed & Sukaram, Criminal Defense Attorneys – San Jose Office
1625 The Alameda, Suite 405, San Jose, CA 95126
(408) 217-8818

Ahmed & Sukaram, Criminal Defense Attorneys – Redwood City Office
600 Allerton St Suite 201G, Redwood City, CA 94063
(650) 299-0500