The Colorado attorney general’s office says the lawsuit alleges “that Colorado’s Amendment 64 and its implementing legislation regarding marijuana is unconstitutional under the Supremacy Clause of the U.S. Constitution.”
It’s a solid argument, but I think they leave themselves open to the counter-argument that the federal laws must be constitutional themselves in order to claim supremacy.
Good. That steaming pile of socialist sophistry we refer to in polite company as the "New Deal Commerce Clause" needs to be hauled out and stomped into a mud hole, and then the mud hole stomped dry.