Rival internet service providers BT and TalkTalk have buried their differences and teamed up to challenge the Digital Economy Act in the High Court.The act, which was one of the last pieces of legislation passed under the previous Labour government, seeks to clamp down on copyright infringement by heavy users of peer-to-peer file sharing networks.Internet service providers (ISPs) will be expected to cut off persistent offenders but BT and TalkTalk, along with many other ISPs, argue that the act runs counter to the European directive on e-commerce, which posits that ISPs are mere conduits of content, and are therefore no more responsible for what gets carried on their networks than are road builders for what gets transported on roads."The two companies believe that provisions in the Act, aimed at the prevention of online copyright infringement, received insufficient scrutiny before being rushed through into law at the tail end of the last Parliament," a BT statement said.The two companies believe the measures proposed by the act could breach citizens' basic rights and freedoms and could have an impact on BT and TalkTalk's businesses.The pair appear to have the support of deputy prime minister Nick Clegg, who is on record as saying that the Act "badly needs to be repealed".