SNP members will this week be urged to back the legalisation of cannabis for medicinal use.
The party will vote at its autumn conference on whether the Class B drug should be available by prescription on the NHS.
First Minister Nicola Sturgeon previously said she was not in favour of general decriminalisation of the drug, but added there is a specific case for medicinal use.
Health policy is controlled by Holyrood but the criminalisation of drugs is overseen by Westminster.
The motion from the Ayr North branch of the SNP said that, where appropriate, cannabis should be decriminalised for medical use and available on prescription.