Sources of Compliance Guidance for Website Owners
Probably the most complete English language guide to cookie law compliance from an official source is the document produced by the UK Information Commissioner’s Office (ICO).
The ICO is the UK’s Data Protection Authority, and is responsible for enforcing the cookie law in the UK. Although their guidance really only applies to the UK law, it’s a very good starting point.
The other key organisation that issues advice and guidance for the whole of the EU is the Article29 Working Party. This body is made up of representatives of the data protection authorities in each EU member state. Although their opinions and publications themselves carry no official legal weight, they are an authoritative source on the interpretation of the legislation.
Possibly their most important document for website owners is their published opinion on what types of cookies can be included in the strictly necessary exemption from the need for consent.