If the supreme court says abortion is illegal, even if states pass laws saying it's legal, you can still be prosecuted under the federal law. Federal Law takes precedence, always.
As for Marijuana, if a state makes it legal, you can be prosecuted under Federal law, but State agencies such as local and state law enforcement, cannot aid the federal government in any way. (They still do, but they are not allowed.)
Seeing as the laws were passed by the taxpayers in the state, and all state law enforcement is paid by the state taxpayers, it makes perfect sence. But that does not stop dpartments such as homeland security, the FBI, or the ATF from enforcing federal law.