Uh, you should always seize the keys. Too many bad things can happen. At the very least they can wind up getting picked up by the cops and you'll be driving them everywhere anyway so... yeah.
Well if you don't care then don't take them. If you do, then take the keys. Not a tough choice.
I try to stop them..get someone else to drive..tell them lets go get something to eat before you go...I try what ever it takes to get them home safe..
Yes I have..she was arrested about 10 mins after she left the bar..