The US government is planning on categorizing marijuana as a low-risk drug, broadcaster NBC News and the Washington Post newspaper reported on Tuesday, citing sources familiar with the development. In the US, access to controlled substances is regulated by a law that groups drugs into five different categories. So far, marijuana has fallen into the highest category of illegal drugs, Schedule I, which also includes heroin, ecstasy and LSD. That’s in a category above cocaine. According to the reports, marijuana is to be downgraded to a Schedule III drug in future and would therefore be on a par …