The deaths of two men in central Queensland after they smoked synthetic cannabis highlight the need to regulate marijuana and allow its controlled sale, the president of the Australian Drug Law Reform Foundation says. Dr Alex Wodak said it was extremely difficult to determine the substances in synthetic cannabis, making its effects unpredictable and treatment for unwanted reactions difficult. He said people were drawn to synthetic drugs because they could be easier to obtain and because of the misguided perception they were legal and safe.