The Directive 2004/22/EC of the European Parliament and of the Council of 31 March 2004 on measuring instruments is relevant.
The BBC News reported in 2007 that it would come into force:
Brewers battle to save Crown mark
Nine of Britain's biggest brewing and pub companies are urging the prime minister to stop the Crown symbol on beer glasses being scrapped.
The Crown has been in use since 1699 as a guarantee of the size of pints and half pints. But now it is set to disappear, replaced by a European Union-wide "CE" mark instead.
Campaigners say the change is another example of "excessive interference" by bureaucrats in Brussels. The EU's Measuring Instruments Directive came into force last October and requires the UK to phase out the Crown in favour of the Conformite Europeenne logo.
The Directive's scope does include drinking glasses:
Capacity serving measure
A capacity measure (such as a drinking glass, jug or thimble measure) designed to determine a specified volume of a liquid (other than a pharmaceutical product) which is sold for immediate consumption.
Whether the previous Crown imperial measure mark was banned, isn't obvious. The next clause suggests that Member States may decide not to use the CE mark:
(6) The principle of optionality introduced by this Directive, whereby Member States may exercise their right to decide whether or not to regulate any of the instruments covered by this Directive, should be applicable only to the extent that this will not cause unfair competition.
However it also states that Member States must not prevent the use of the CE mark:
(17) Member States should not impede the placing on the market and/or putting into use of measuring instruments that carry the "CE" marking and supplementary metrology marking in accordance with the provisions of this Directive.
but these next clauses seem to contradict (6) above:
(18) Member States should take appropriate action to prevent non-complying measuring instruments from being placed on the market and/or put into use. Adequate cooperation between the competent authorities of the Member States is therefore necessary to ensure a Community-wide effect of this objective.
(21) National specifications concerning the appropriate national requirements in use should not interfere with the provisions of this Directive on "putting into use".
This next clause seems to suggest that other marks in addition to the CE mark may be used, but not so as to confuse:
- The affixing of markings on a measuring instrument that are likely to deceive third parties as to the meaning and/or form of the "CE" marking and the supplementary metrology marking shall be prohibited. Any other marking may be affixed on a measuring instrument, provided that the visibility and legibility of the "CE" marking and the supplementary metrology marking is not thereby reduced.
I presume this means that the drinking glass cannot bear two certification marks (which might have differing regulations about accuracy etc).
The document is a legal document, and so the meanings may not be obvious to the casual reader.
I can't find any clause that specifically bans the use of the Crown mark, but a lawyer might argue that the clauses all together do amount to that.
I would welcome anyone else throwing more light on the matter (especially if it has a lovely golden hue to it).