Legal Question in DUI Law in California

What do you mean "open garage?" If it's inside the garage and it's your private property, there's nothing wrong with that. As long as it's not on public property.

Mr. Doan is correct, but also assuming you are 21 and not subject to a probationary restriction against drinking at all. It does not matter whether the door is open or not. People can see you in your kitchen drinking beer through a window too.