They can't manifest into substantive action, Rohrabacher-Farr prohibits it. That's why Sessions keeps harassing Congress to withdraw the prohibition, so he can use DoJ funds to prosecute both recreational and medical marijuana possession, distribution, production.
> They can't manifest into substantive action, Rohrabacher-Farr prohibits it.
Rohrabacher-Farr only applies on its face to state medical cannabis laws, and in any case Trump's signing statement on the spending bill containing the first renewal during his administration implied that the administration views the provision as unconstitutional. So, there's certainly action that the DoJ could take consistent with the administration rhetoric, from a couple different angles. It would hardly be the only example of this administration aggressively probing the limits of its power until and unless explicitly constrained by the courts.