The federal legalization of marijuana is an imperative step towards liberty, and respecting the will of the American People and the powers delegated to the individual states by the 10th Amendment. Seven states and The District of Columbia have legalized marijuana for recreational uses as of our last election cycle. However, the Federal Government still has regulations prohibiting the manufacture, trade, sale, possession or use of Marijuana -- despite the state laws allowing it.
The existence of a federal prohibition was seemingly a non-issue under the Obama Administration, which had chosen not to enforce those laws in states in which the citizens had decided to allow the use of marijuana for recreational purposes -- but those laws are still on the books. President Trump has indicated a willingness and inclination to instruct the Department of Justice to take action against states that have legalized marijuana, under the lead of Attorney General Sessions. This move would infringe upon peoples' rights to exercise their freedoms.
This prohibition will not stop anyone from using marijuana, just as it being illegal previously did not stop it from being a billion-dollar-industry. Prohibition doesn't eliminate the product or service; rather, it simply forces it to the black market. The black market is a market with no controls or methodology for conflict resolution. There is no quality control or complaints process in the black market, which leads to unknown drug composition, and no possibility for civil litigation as a form of complaint against a competitor or supplier. Prohibition makes the market dangerous, and endangers the lives of those who participate, but it does not stop them from participating.