In its ruling of 25 June 2014, the US Supreme Court held that the unlicensed TV streaming service Aereo is illegal. Aereo's service amounts to "public performance" of broadcasters' copyright works and therefore requires prior authorisation under the US Copyright Act.

Aereo's service allows its subscribers, against a monthly fee, to watch TV programmes over the Internet at almost the same time that the programmes are broadcast free-to-air. However, where cable companies retransmitting broadcast programmes are obliged under US law to pay retransmission fees to the broadcasters, Aereo claimed that the technological configuration of its streaming service was constructed in a way that it transmitted a single copy to a single subscriber and therefore did not engage in a "public performance".

Television broadcasters sued Aereo for copyright infringement and took the case all the way to the Supreme Court. In its ruling, the Supreme Court held that Aereo's service does amount to "public performance" of broadcasters' copyright works, with the service showing an overwhelming likeness to cable retransmission.

It is the Court’s opinion that Aereo "performs" and does not merely supply equipment. The user's involvement in operating the equipment and selecting content was considered by the Court the sole technological difference between Aereo and cable companies.

Aereo's performance was also considered to be "to the public". The subscribers to whom Aereo transmits form a large number of persons who are unrelated and unknown to each other. For the Court, the specific setup of the Aereo service using individually-assigned antennas, transmitting user-specific copies to only one subscriber amounted to "behind-the-scenes technological differences" that do not distinguish Aereo from cable retransmission systems. The US legislator would as much have intended to protect a copyright holder from the unlicensed activities of Aereo as from those of cable companies.

Leading up to this highly anticipated decision, some  concerns had been raised that the decision against Aereo might have unfavourable consequences on new technologies (such as "cloud computing"). The Court added some reassurance by stating that given the limited nature of this holding it does not believe its decision will discourage the emergence or use of different kinds of technologies.

The Supreme Court ruling against Aereo (overturning the decision of the Court of Appeal) is a major victory for US television broadcasters.