They'll just drive anyway. Have you ever heard of this? I thought this was what they did. I don't understand. Is this not a common pattern? Why would they suddenly start obeying the "rules of the road?"
We had the same problem with my mom and my dad had to take her keys away and hide his to keep her from leaving. Don't feel alone it's pretty common I think. Oh and BTW I'm fairly sure that taking keys away is not the right way to handle it unless it is an isolated instance of them being drunk and you stopping them from driving.