The divisive Digital Economy Bill, the Labour government's twilight attempt to curb online piracy, is facing renewed opposition from major ISPs.
BT and Talk Talk are demanding that the high courts now review whether the anti-filesharing act contradicts EU legislation, claiming it was "rushed through", had "insufficient scrutiny" and may impinge upon "basic rights and freedoms."
The controversial bill made it through the Commons following a two hour debatein April with a voting majority of 142, despite MPs receiving over 20,000 letters asking for more consideration.
Many were angered that 64 per cent of MPs did not attend the debate, with 187 of those who did vote on the bill's passage not arriving until the end of the hearing.
BT and Talk Talk are claiming that subsequent powers to disconnect users accused of infringing copyright, and to block access to sites deemed to be hosting illegal content, have been enabled prematurely.
The complaint centres around the fact that ISPs with customer bases of 40,000 or more will be required to find and blacklist offenders, as well as passing their details onto copyright holders for possible legal action.
"It means we could have huge swathes of customers moving to smaller ISPs to avoid detection," Andrew Heaney, executive director of TalkTalk, told the BBC.
Also claiming that the bill may be in violation of EU stipulations on electronic privacy and that ISPs should be considered mere conduits, he was concerned that the onus was on firms such as his, rather than on copyright enforcers such as the BPI. "It is outrageous that they are coming begging at our door but are not helping themselves," he said.
Added Talk Talk Chairman Charles Dunstone to The Times, "The Digital Economy Act's measures will cost the UK hundreds of millions and many people believe they are unfair, unwarranted and won't work. Innocent broadband customers will suffer and citizens will have their privacy invaded."
While the new government does have the option to repeal the act, it seems currently uninterested in doing so - despite deputy prime minister Nick Clegg having been an opponent of the bill before its passage. "It badly needed more debate and amendment," Clegg claimed at the time.
In a statement to the BBC, the government's Department of Business, Innovation and Skills said, "The Digital Economy Act sets out to protect our creative economy from the continued threat of online copyright infringement, which industry estimates costs the creative industries, including creators, £400m per year.
"We believe measures are consistent with EU legislation and that there are enough safeguards in place to protect the rights of consumers and ISPs and will continue to work on implementing them."