If Bluesfest banned law chairs, and someone somehow brought in a lawn chair, Bluesfest could eject them from the site. They could probably rip up the ticket too. They'd likely just firmly ask the patron to check the chair at coat check in the museum for the rest of the day and not bring it tomorrow. For smokers, same thing - they can eject the patron and likely take away the ticket, but I think that's a bit heavy-handed for the first year unless it's a repeat offender or the person's being a dick about it.