You've probably been to a restaurant where the proprietors advertise or mention that they do not have an Ohio liquor permit, but that they allow customers to bring their own alcohol, or "BYOB". However, few people stop to think whether this process is legal.
As a general rule, Ohio law prohibits the public consumption of alcohol, unless otherwise provided. Unfortunately for many Ohio restaurants, there is no such thing as a legal BYOB policy.
Perhaps the best way to think of alcohol consumption in Ohio, is that it is all illegal, subject to express exceptions. That is, you will not find express laws stating that BYOB policies are illegal in Ohio, however, all public consumption of alcohol is illegal unless it occurs on an expressly permitted premises.
This begs the question - what about private parties? In general, private parties are fair game for alcohol consumption (assuming alcoholic beverages are not sold), unless they are held on the premises of a liquor permit holder, which are of course, reserved only for alcohol sales.