You're walking down the street with your buddy. He's smoking a doobie. There's just the two of you.
Three police officers come up to you guys and arrest your buddy. You don't try to fight, flee, or anything else, and haven't done anything wrong. Can they put you in cuffs?
No. Not in America, anyway.
The depressing thing about the opinion, however, is that it takes nine pages to explain why not.