Appellants complain that DOJ is spending funds that have not been appropriated by Congress in violation of the Appropriations Clause of the Constitution. See U.S. Const. art. I, § 9, cl. 7 (“No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law ….”)…. [I]f DOJ were spending money in violation of [§ 542], it would be drawing funds from the Treasury without authorization by statute and thus violating the Appropriations Clause. That Clause constitutes a separation-of-powers limitation that Appellants can invoke to challenge their prosecutions….

Thus, in order to decide whether the prosecutions of Appellants violate § 542, we must determine the plain meaning of “prevent any of [the Medical Marijuana States] from implementing their own laws that authorize the use, distribution, possession, or cultivation of medical marijuana.” … “[I]mplement” means:

In sum, § 542 prohibits DOJ from spending money on actions that prevent the Medical Marijuana States’ giving practical effect to their state laws that authorize the use, distribution, possession, or cultivation of medical marijuana….

[By prosecuting state-authorized medical marijuana users,] DOJ, without taking any legal action against the Medical Marijuana States, prevents them from implementing their laws that authorize the use, distribution, possession, or cultivation of medical marijuana by prosecuting individuals for use, distribution, possession, or cultivation of medical marijuana that is authorized by such laws. By officially permitting certain conduct, state law provides for nonprosecution of individuals who engage in such conduct. If the federal government prosecutes such individuals, it has prevented the state from giving practical effect to its law providing for non-prosecution of individuals who engage in the permitted conduct.

We therefore conclude that, at a minimum, § 542 prohibits DOJ from spending funds from relevant appropriations acts for the prosecution of individuals who engaged in conduct permitted by the State Medical Marijuana Laws and who fully complied with such laws….

[But] DOJ does not prevent the implementation of rules authorizing conduct when it prosecutes individuals who engage in conduct unauthorized under state medical marijuana laws. Individuals who do not strictly comply with all state-law conditions regarding the use, distribution, possession, and cultivation of medical marijuana have engaged in conduct that is unauthorized, and prosecuting such individuals does not violate § 542….

We therefore must remand to the district courts. If DOJ wishes to continue these prosecutions, Appellants are entitled to evidentiary hearings to determine whether their conduct was completely authorized by state law, by which we mean that they strictly complied with all relevant conditions imposed by state law on the use, distribution, possession, and cultivation of medical marijuana. We leave to the district courts to determine, in the first instance and in each case, the precise remedy that would be appropriate.

We note the temporal nature of the problem with these prosecutions. The government had authority to initiate criminal proceedings, and it merely lost funds to continue them. DOJ is currently prohibited from spending funds from specific appropriations acts for prosecutions of those who complied with state law. But Congress could appropriate funds for such prosecutions tomorrow.

Conversely, this temporary lack of funds could become a more permanent lack of funds if Congress continues to include the same rider in future appropriations bills. In determining the appropriate remedy for any violation of § 542, the district courts should consider the temporal nature of the lack of funds along with Appellants’ rights to a speedy trial under the Sixth Amendment and the Speedy Trial Act.

[Footnote: The prior observation should also serve as a warning. To be clear, § 542 does not provide immunity from prosecution for federal marijuana offenses. The CSAprohibits the manufacture, distribution, and possession of marijuana. Anyone in any state who possesses, distributes, or manufactures marijuana for medical or recreational purposes (or attempts or conspires to do so) is committing a federal crime. The federal government can prosecute such offenses for up to five years after they occur.

Congress currently restricts the government from spending certain funds to prosecute certain individuals. But Congress could restore funding tomorrow, a year from now, or four years from now, and the government could then prosecute individuals who committed offenses while the government lacked funding. Moreover, a new president will be elected soon, and a new administration could shift enforcement priorities to place greater emphasis on prosecuting marijuana offenses.

Nor does does any state law “legalize” possession, distribution, or manufacture of marijuana. Under the Supremacy Clause of the Constitution, state laws cannot permit what federal law prohibits. Thus, while the CSA remains in effect, states cannot actually authorize the manufacture, distribution, or possession of marijuana. Such activity remains prohibited by federal law.]