Sweet homemade blackberry wine is far better than any wine you can buy, in my personal opinion. If you can get the berries either by luck in finding wild bushes or buying them, you need to make this wine. You don’t need a license and as long as you don’t sell it you are fully within the law of most states.
Most store bought wine is full of sugar, additives, sulfates, preservatives to keep stable for a long shelf life in stores, homemade wines do not need those ingredients. Man That Stuff Is Good website shared the in depth instructions on how to make Blackberry wine and it turned out absolutely delicious.