[INJ] I can appreciate your thinking, although I think a litre is a bit big for responsible consumption of draught beer. I don't want the law to change for a few reasons. One of which is that I seem resistant to change in general and I "like" pints. Also, I'll (probably) have to re-stock all my beer glasses, which could cost me over 500 quid. It's currently a little frustrating that I can't sell a pint or half-pint of lemonade. I can sell a "large" or "small" lemonade, in pint and half-pint glasses. Or I can sell "568ml" or "284ml" in the same glasses. As far as I know, only beer, cider and milk can be legally be sold in pints in the UK, although there is no such restriction throughout the rest of Europe, where it is perfectly legal to use Imperial measures for anything. Curiously "shandy and any other beverage of which beer is a constituent part" counts as beer for the Weights and Measures (Beer and Cider) Act 1998. So anything with a bit of draught beer in it, should be served in thirds or multiples of halves. How odd. I have in mind things like the Irish method of serving a Black Russian (with a Guinness head on it). Sorry, I've started thinking out loud now.
[Phil] I did not say abandon the pint glass in pubs, the continentals do use them but you never actually get a pint in them - they do like their froth. What I was alluding to was the indecision of whether we are a metric or imperial nation. At the moment it is a=half cocked with some things sold in imperial and some in metric (metric martyrs in the marketplace for example). There needs to be clear leadership. As for selling liquids in taverns the UK still has a half-cocked approach. Spirits are metric; beer is imperial. While I agree that spirits should be sold in standard sizes (many continentals have a relaxed view on what constitutes a measure) I think that draught beer could be sold in whatever size glass that the licensee chooses - provided that it is priced accordingly and clearly stated.
Softers) Uniformity of units is not necessary except to the tidy-minded. All you need to know is what you're getting and for all users to be familiar with those units. A pub that sold beer in metric units would very likely lose a lot of customers. If it is not necessary to change it is necessary not to change. A pint glass of whatever style is a very familiar object (shut up at the back). This keeps people happier except for the aforesaid tidy-minded commitee members and they are very few in number. Actually we should use cubic attoparsecs (19.34 to the pint).