I could kill all the pub landlords who continue to serve him when he's had 6 pints and 3 whiskeys. I'd murder the jerks at the corner shops who sell him 6 cans of lager, after he's left the pub. I wish police would prosecute these people more regularly. It's better here (in the country I'm from) - bartenders are fined for that. In the UK, these dangerous opportunists seem to get away with it, scot-free.
In all likelihood, if the law were enforced, he would buy the 6 cans before he went to the pub, or take a flask of vodka to the pub, or stay at home and drink cheap cider instead. This is from experience. I understand your anger, but it wouldn't change his choices, he's an addict, unless he decides to limit himself, even complete prohibition, wouldn't get between him and a supply of alcohol.
Have you read codependent no more, or looked into al-anon for yourself?