The US supreme court has ruled that Aereo, the TV streaming service backed by media mogul Barry Diller, is illegal. The justices accepted the argument of the major US broadcasters that Aereo's service amounts to a violation of copyright law. Aereo captures the over-the-air signals of network broadcasters and streams them to customers via their computers, smartphones or devices such as Apple TV or Roku. It has thousands of tiny aerials that it assigns to each of its customers, which allows Aereo to argue that its clients are merely renting antennae of the sort they would otherwise have in their homes. Customers pay between $8 and $20 a month for the service, which includes a cloud-based digital video recorder – far less than the average cable bill. The company does not pay fees to the media companies whose signals it redistributes, while the cable companies pay about $3bn.