In a judicial review into the DEA in April the High Court said that it was acceptable for copyright holders to use personal data of ISP customers to pursue copyright infringement cases in court.
In its ruling the, the High Court said that the Act did not violate EU laws. BT and TalkTalk had argued that the DEA breached users' freedoms and privacy.
BT and TalkTalk said they will ask the Court of Appeal to look at whether the DEA breaches the EU's Technical Standards Directive, Authorisation Directive, E-Commerce Directive, and the Privacy and Electronic Communications Directive.
"BT and TalkTalk believe that the DEA measures aiming to prevent online copyright infringement are inconsistent with European law." BT and TalkTalk said in a joint statement.
"Quite apart from the potential impact on their businesses, BT and TalkTalk believe the DEA could harm the basic rights and freedoms of ordinary citizens. Many MPs of all parties, consumer groups and other communications providers share this view," BT and TalkTalk said in their statement.
A part of the DEA forces Ofcom, the UK's media regulator, to write new regulations governing against online copyright violations.
In a draft code of practice published last year, Ofcom said ISPs had to hand over details of customers who were illegally filesharing to copyright holders to allow them to sue. The UK Government said in April that it was delaying the introduction of Ofcom's code because of the judicial review.
If Ofcom's code is enacted ISPs could have to disconnect users if they are found to be illegally downloading copyrighted material.
The EU Privacy and Electronic Communications Directive governs what information can be gathered from electronic communications and says that ISPs should not be responsible for material sent over their network unless informed about infringements of the law.
The two ISPs said that they would not challenge the High Court's findings that the DEA's measures are proportionate.
"Both companies continue to take the view that the regime represents a disproportionate interference with the rights of internet service providers, subscribers and internet users and with the concept of freedom of expression," BT and TalkTalk said.
"They recognise, however, the Court’s view that there is an exceptionally high threshold to show that this legislation was not a proportionate response prior to the code of practice being published and have concluded not to pursue leave to appeal on this ground," BT and TalkTalk said.
Under Ofcom's code of practice warning letters will be sent to internet users thought to be involved in copyright infringement. Quarterly reviews of the process will evaluate the success of the letter writing campaign and the Culture Secretary will have the power to demand that ISPs disconnect persistent offenders.
A spokesman for the Department for Culture, Media and Sport (DCMS) told OUT-LAW that it will be 2012 before any enforcement measures are taken against copyright infringers.
"We are expecting the first letters to go out in the first half of next year," the DCMS spokesman said.
"We cannot speculate as to whether any appeal [by BT and TalkTalk] would delay this," the spokesman said.
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