The states can legalize marijuana, meaning that the state police and courts no longer prosecute it. But currently the federal government can still come in and

The states can legalize marijuana, meaning that the state police and courts no longer prosecute it. But currently the federal government can still come in and make arrests, although they typically choose not to enforce the law, because doing so would be politically unpopular. Plus it's not like there are FBI agents walking the beat trying to make low-level drug busts. The most confusing is Washington D.C., a federal territory, which has been granted limited home rule. They voted in a referendum to legalize and regulate marijuana, but then were prohibited by Congress from spending any money to actually draft the necessary regulations. The result is that marijuana is illegal to buy or sell but legal to possess or use, except in many public parks which are technically part of the federal National Park system.