TV service Aereo is breaking copyright laws by streaming broadcast channels without paying, the U.S. Supreme Court ruled Wednesday.

Justices ruled 6-3 on the case, reversing a lower court ruling.

Using thousands of miniature TV antennas, Aereo scoops up the freely available signals of local stations in cities like New York and Boston. Then it delivers the signals to the smart phones, tablets or computers of paying subscribers.

TV station owners, including major media companies like The Walt Disney Company, claimed Aereo is violating copyright by allowing "public performances" of their shows.

Aereo said it was only enabling only private screenings, just like off-the-shelf TV antennas do, but with added convenience.

Its attorneys argued the startup didn't need to pay fees like the cable companies because the broadcast signals are free.

During oral arguments in April, several justices appeared skeptical of Aereo's business model.

"Your technological model is based solely on circumventing legal prohibitions that you don’t want to comply with," Chief Justice John Roberts told the company's attorney.

Observers have said a loss would likely force Aereo to shut down.