Government plans to disconnect illegal filesharers from the internet need to be more technical, it has been suggested.
Which?'s Head of Legal Affairs, Deborah Prince, said that while the digital economy bill is generally good, it fails to address "the technical practicalities" needed to make the legislation work.
She told the Daily Telegraph that a key issue is how the government intends to correctly identify those guilty of sharing music or films illegally.
"The law needs to be clarified to ensure there is a general acceptance that just because illegal activity may have happened on an internet connection the account holder is not necessarily held accountable as someone may have hacked into that person's network," she added.
At the end of last year, broadband provider TalkTalk estimated that up to seven million homes and businesses could be vulnerable to Wi-Fi hijacking.
The company is one of the biggest critics of the digital economy bill and launched its Don't Disconnect Us campaign in response to the proposals.