IM26 by District 24 Senator Mary Duvall. IM26 passed by the voters last fall legalizes medical marijuana in South Dakota. While the measure itself goes into effect on July 1, that does not automatically mean that those who want to use medical cannabis will be able to go to a local dispensary and buy some starting on July 1. The measure itself contains several specific dates for implementing various portions of the law. It also creates an oversight committee to monitor implementation and to make recommendations to the Legislature and the Department of Health on possible improvements.