[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).
I've written about this before, but beer sizes in Australia are weird and wonderful. In Melbourne the standard drink is a pot, which is 285ml. In Sydney this same measure is called a middy, in Hobart a ten and in Darwin a handle, while in Adelaide it is called a schooner (or even an up-sized schooner as the old schooner was 255ml or 9 fl oz), however, asking for a schooner in any other city will get you 425ml. If you want 425ml in Adelaide you will need to ask for a pint, but if you ask for a pint in any other city you get 570ml. To get this size of drink in Adelaide you need to ask for an Imperial Pint. In Darwin and north Queensland (where men are men and sheep are worried) you also get a 7, which is 200ml (probably because a small measure of beer stays cold, while a big beer goes warm over time - not because they like drinking girl sizes). It makes travelling in Australia more adventurous.
(nfras) How can a small measure stay colder for longer than a large one? It doesn't; you drink it quicker. The small Queensland measures wouldn't go down too well in Carshalton (London Borough of Sutton) where not only are men men but women are as well.