Is this fair to do to my friend, and should we talk to her about it?

i have gone though this with a friend of mine, but hers was drinking. The fairs around here keep cops in them for things like this, we told her before hand that she is responsible for herself and that if she goes and does the drinking then she will not be welcomed to stay with us cause we didn't want to get kicked out but that she could meet us back at the car to ride home. each person is responsible for their own actions, and sometimes u have to think about ur self cause u don't want to ruin ur good time because of their actions. i hope this helped and enjoy the fair!