Pragmatically, this is a question of enforcement. Federal LEOs shall not compel state LEOs to enforce federal law. See https://en.wikipedia.org/wiki/Posse_Com

Pragmatically, this is a question of enforcement. Federal LEOs shall not compel state LEOs to enforce federal law. See https://en.wikipedia.org/wiki/Posse_Comitatus_Act https://en.wikipedia.org/wiki/Posse_Comitatus_Act and the 10th Amendment for why, but this fact has very long precedent. So if nice Mr DEA man goes to the state police and say "help me bust these grow operations", the head of the state police says "go piss up a rope, those are tax-paying law abiding citizens who are breaking no law I have the responsibility to enforce." And this is called state's rights. Rhetorically I am well within the realm of sanity to describe purchasing weed at the dispensary down the street as legal. Feel free to insert the implicit footnoted "persuant to the laws of the state of oregon" in your head, if you like, for completeness.