The top European Court has, rather unsurprisingly, ruled that UK-based website TVCatchup cannot transmit live TV streams online without the permission of broadcasters.
In a case brought against the site (and dozens of others) by ITV, Channel 4 and Channel 5, the European Court of Justice ruled that as "authors" of the content, they have the right to forbid its use elsewhere.
TVCatchup had argued that licenses granted to the channels by Ofcom also covered "subsidiary services" such as its own and claimed it was not breaking copyright law by re-transmitting free-to-air broadcasts.
However, the court said TVCatchup, and other sites of its ilk, "can't escape the authorisation of the copyright holders" and must obtain permission if they wish to continue transmitting shows.
In a statement, on behalf of all three broadcasters, ITV said it was now free to pursue legal action against unauthorised sites that sought to broadcast its content.
The spokeswoman said: "ITV, Channel 4 and Channel 5 welcome the judgment by the European court of justice. The judgment makes it clear that, subject to some limited defences, broadcasters and content producers should be able to prevent unauthorised streaming of free-to-air channels.
"We now look forward to the UK court's implementation of this judgment. We reserve the right to pursue any site or service we believe to be infringing our copyright or using our content in an unlicensed, illegal capacity."
Defiant TVCatchup director Bruce Pilley insisted that the service was operating within the law and claimed the ECJ's ruling would only affect around 30 per cent of its 12 million members.
He said: "TVCatchup.com is here to stay, we are not thinly disguised purveyors of filth, we remain Europe's first and only legal internet cable service and the ECJ opinion affects only a handful of channels we carry."
Legal experts say the verdict may have greater implications, with other broadcasters going after sites that stream live sport online.