Four US networks Fox, CBS, ABC and NBC sued HD internet television provider FilmOn for violating the networks' copyright laws by taking their signals and streaming them without permission or compensation.
A US judge on Monday issued a temporary restraining order against FilmOn to stop the streams.
The broadcast networks have also filed a suit against streaming company Ivi, which they claimed has also been streaming the signals of TV stations illegally.
FilmOn and Ivi reportedly take free over-the-air broadcast signals and convert them to online streams. The companies have claimed that it's their right to distribute the network material under a provision in the US Copyright Act.
Seattle-based Ivi argued that it is not governed by a separate communications statute that requires cable and satellite companies to negotiate licences with content owners before transmitting their networks, according to a report on B2B media marketing company TMC.