Frequently asked questions Brief History of Ohio Medical Marijuana Laws Here is an overview of the medical marijuana laws in Ohio: 2016 – Governor John Kasich signs House Bill 523 (HB 523), allowing for the use of marijuana for medical reasons. HB 523 allows for a patient to carry a 90-day supply of cannabis. Smoking cannabis is not approved, and only oils, patches, herbal material and tinctures are approved methods.