Are fermented home-canned berries safe? I just opened home-canned blueberries and blackberries. They are probably 5 years old, and taste like alcohol. Are they safe to eat? I don't know anything about the original canner's intent.

The blueberries still have their skins and seem to be in juice.
Unless you know that the alcohol was added by the cook at the time of canning, I’d treat it as a sign that “something” happened. And in canning, “something” is always considered bad, because it means the food was in uncontrolled conditions. 

I’d stick to the golden food safety rule of “when in doubt, throw in out”, just to be safe.