Confusion with laws

Hi all, new member here. I was under the impression that Marijuana is still illegal in the United States. However, someone said on the closet cultivation forums said you can grow it if you have a med card, and he doesn't advocate any breaking the law. So I was just curious if it is legal to grow marijuana in the United States with a med card. Not that I'm trying to acquire one, just curious as to the laws.

State laws vary in the US but, i'm fairly sure, the feds can arrest you in any state for cultivation, if they choose to.

Federally illegal. Some states have passed medicinal MJ laws but you still have local authorities violating laws by arresting legal growers and users. The fight still goes on.