No amount of legislation or schemes will stop people behaving this way.
The simple fact remains that our society has developed a dependant culture on alcohol due to there being very little other opportunity for society to integrate; we have no town-halls for example and neighbours rarely speak to one another - it is the curse of modern urban sprawls. Couple this absolute 'need' to socialise, with the issues of finding a partner (and the bravado and therefore violence it will inevitably cause); it literally becomes a lifestyle.
The absolute problem however, exists with the individualistic selfishness which pervades our daily lives. People simply will not take responsibility for their own actions anymore. How many people screaming and fighting would be just as quick to claim that they are responsible adults and not acting like a spoilt, misbehaving child?
Going 'out' is about socialising, having fun and to many: getting their end away. Alcohol merely complicates this quagmire, so addressing it in a totalitarian manner will not solve it; the issue lies much deeper at a cultural and social level.
People need to grow up and take responsibility for their own actions. People need to recognise that society does exist and they are not the most important fish in the sea - they are just another fish, nothing more. How many people here for example, find it incredibly easy to avoid violence, arguments and generally acting like a complete idiot when they choose to go out? It's one thing to let your hair down, and another to start scuffling inside a club because someone's eyeing the same bird as you. It's pathetic: grow up.
Police presence is completely irrelevent when the same people will inevitabley be acting up again the following weekend or perhaps many months later when an arrest seems a distant memory. As far as legislation goes, we need to actually come down harder on violent drunks; it is not hard to behave when you're drunk. That said, emotions that come out whilst drunk are always bubbling away under the surface daily, so those who do look for trouble are probably leading very poor lives. However, that doesn't give them the right to smash someone's face with a bottle simply because they want to prove that they're 'harder' and more worthy of sex to that blonde bint in a miniskirt with fag in hand who's complaining about breaking her damn nail. The consequences of people acting like idiots need to and can easily be addressed. This of course, doesn't necessarily always mean jail-time: community work and schemes (such as talking to professionals or victims of their actions) to make individuals realise that they are not the centre of the universe will perhaps go a long way to help.
I understand that sometimes people have problems in their life which will cause them to behave in a non-conformist, unaltruistic, and selfish way - some people may take drugs to try and escape their problems - but part of being a functional adult is learning to deal with these issues both productively and safely. Society could go a very long way to introducing more support for people when they need it. Issues of mental health for example, are still very difficult to deal with and due to their nature often leave an individual feeling peverse and highly isolated. Society needs to have a structure in place whereby it seeks out such individuals and gives them the help they need while they are still personally in a position to not be dependant on such help. Indeed, society also needs to learn to overcome its fear of helping itself. Too often (I'm guilty of this too) we avoid uncomfortable situations which we could perhaps have helped make the world of difference. Sometimes, a complete stranger simply giving a toss can be the most profound thing.
That said, many of the people (from my experience) who are predisposed to violent encounters on a casual night-out tend to be from a popular sub-culture which tends to glamourise wealth, strength and 'respect'. Basically, they're idiots because they cannot or will not see beyond their own little circle of friends. They need a kick up the backside to snap out of it and society instead of promoting it, needs to actually look down on it.
We are not cavemen anymore: we have brains and the consciousness to rise above it. It is simply at the end of the day about choice and strength of character. Perhaps we need to go back to children at primary school and thoroughly drum the lesson into them: you are as an adult by and large who you choose to be. I don't cause violence or harm those around me, I'm considerate of others because that is who I have chosen to be; it's that simple.