I'm confused

Why am I reading of state and local police of a medical mj state arresting medical marijuana patients who are abiding by the state and local laws? Is this "medical marijuana card" just bullshit? Or do cops really let you go if they find you possessing/or growing while abiding by the state law?

It's the DEA you have to worry about. I live in California and in my experience cops don't really care. As long as you have a card from a doctor you're fine. The only people you really see getting hit on by the dea are big time grow ops and certain clubs. You as an individual don't need to worry about it.

That's what I believed. But...go ahead and google or bing search medical marijuana patients being arrested. It doesn't make sense.