The confusion comes after the European Parliament adopted the telecoms directive yesterday, meaning a host of new regulations will come in to force across the European Union over the next 18 months.
By contrast, the European Internet Advertising Bureau has said the directive effectively maintained the existing opt-out regime, making what was once a grey area − whether respecting a user's internet browser settings was seen as enough to comply with regulations − clearer.
Kimon Zorbas, IAB Europe vice-president, said: "The EU legislator kept the existing opt-out regime for cookies and improved it to the benefit of internet users.
"Importantly, business now has a solid legal basis to rely on the browser settings when deploying cookies. This recognises the established practice that web users set their cookie preferences in their settings managers."
However, the new law has been deemed "muddled" by one lawyer specialising in technology, Struan Robertson, a legal director at the law firm Pinsent Masons.
Writing on the Pinsent Mason blog, Out-Law.com, Robertson said that IAB Europe's interpretation is optimistic but attractive.
He said: "It would be better for everyone if the IAB Europe's view is right. It is a pragmatic way to interpret a very bad law that otherwise damages the user experience on websites."
Other new regulations include a requirement for telecoms companies to allow mobile phone users to switch their phone numbers within one working day when switching operators, and a requirement that no internet user have their access cut off by their ISP without evidence that they have been downloading materials illegally.