Cannabis in South Dakota is legal for medical use as of July 1, 2021, having been legalized by a ballot initiative on November 3, 2020. Prior to then, cannabis was fully illegal, with South Dakota being the only U.S. state which outlawed ingestion of controlled substances. Testing positive for cannabis can be a misdemeanor offense. South Dakota would have become the first state in US history to legalize recreational and medical cannabis simultaneously, but an amendment legalizing recreational marijuana that was approved in the same election was struck down as unconstitutional the following February. The challenge claimed the amendment violated Amendment Z, the "Single-Subject Rule". The decision was appealed to the South Dakota Supreme Court, which upheld the lower court's decision on November 24, 2021.
Attempts to delay the implementation of the medical marijuana program to January 2022 failed due to disagreements in the South Dakota state legislature; medical marijuana therefore became legal in July 2021 under the timeframe established in Initiated Measure 26.
South Dakota has one of the harshest cannabis laws in the United States. Possession of any amounts of edibles, hash, and concentrates is a Class 4 felony, punishable by up to 10 years in prison and a fine of up to $20,000.