It's based on the European council's guideline 90/270/EWG. As far as I can tell, it's up to the countries to implement corresponding laws, and at least Germany and Austria have such laws.

Ah, OK. Interestingly, I just checked the UK regulations for this and they define the positioning of the light sources, not the qualities of the screen:

Possible disturbing glare and reflections on the screen or other equipment shall be prevented by co-ordinating workplace and workstation layout with the positioning and technical characteristics of the artificial light sources.