The seat of the federal government is in Washington, D.C. Within the district, residents can grow and use their own recreational marijuana. They can also use medical marijuana.
That's why people feel like the situation is rather complex and potentially controversial. Though those actions are allowed under state law in Maryland and in D.C., marijuana is still illegal at the federal level. That means that the very government that refuses to allow full legalization is run out of a local area that has allowed it, to some degree.
There is even a bit of confusion within the federal government itself. For instance, the Department of Justice has put out a memo telling officials that the federal marijuana ban is still in place, perhaps to show that it can be enforced even if local laws are not broken. At the same time, President Donald Trump has moved in exactly the opposite direction, publicly saying that he thinks the states should get to decide the legality and illegality of it on their own.
The confusion continues within the Justice Department. When asked, officials refused to say they would not go after medical marijuana, stating instead that their plan was to follow the law. That's potentially contradictory, as some pointed out that the law prohibits them from using public funding to prosecute those within the medical marijuana industry.
What seems clear is that there will be plenty of questions if the government decides to take action, as it's unclear exactly what power they have in many cases. If this happens, those facing charges need to know all of their legal rights.
Source: WUSA9, "What a change in pot policy means for DC, Md.," Jan. 04, 2018