Leading internet service providers (ISPs) TalkTalk and BT have come together to battle the government's Digital Economy Act.
The companies have joined forces to file papers with the High Court and call for a judicial review into the legislation, which they believe did not face enough scrutiny before it was rushed through at the end of the last government.
BT and TalkTalk have suggested measures included to tackle online filesharing could have a negative impact on both individuals and businesses.
The ISPs have also suggested that clarity is needed over the legislation, particularly as they believe it may not be compatible with European rules over privacy.
Gavin Patterson, Chief Executive Officer of BT Retail, said: "It's disappointing that we feel the need to take action but we feel we have no choice. We have to do this for our customers who otherwise run the risk of being treated unfairly."
Earlier this year, TalkTalk held a briefing in Westminster to highlight how the Digital Economy Act may just lead to the creation of new tools which allow people who share files to remain undetected.