Subscribers can enjoy a low-cost alternative to watching television by streaming it through their computer, tablet or smartphone. But, broadcast companies aren't happy about it and they're suing the service.

Aereo Inc. pays nothing to the major broadcast companies for their programming. In turn, they can provide their streaming service to subscribers for only $8 per month.

Broadcasters say Aereo is stealing their copyright-protected programming and rebroadcasting it to subscribers. The case will head to the U.S. Supreme Court for a final decision.

Aereo says it's not doing anything wrong. They are taking free-of-charge programming and not premium cable channels.

On Tuesday, the case heads to the Supreme Court for oral arguments where it will be determined if Aereo is indeed violating terms of the federal Copyright Act or just providing customers with an alternative to antenna TV.

Broadcast companies offer the basic channels to any TV with an antenna and digital converter box, but what about cable? Broadcast companies charge hefty prices, sometimes even blacking out their channels, to cable companies. With Aereo, broadcast companies will have less power to charge those hefty fees and cable companies won't be able to increase their rates in response.

Already a big issue, enforcement of copyright protections could be jeopardized if Aereo wins.

"Aereo has built a business out of retransmitting broadcast television to members of the public without seeking authorization from or paying compensation to copyright holders," Washington Appellate Lawyer Paul Clement says in his brief on behalf of ABC, CBS, NBC, FOX, and other major broadcast companies seeking to force Aereo to pay up.

Clement says what Aereo is doing is clearly barred under the Copyright Act. The Copyright Act prohibits the transmittal of a copyright-protected performance to the public without first getting permission.

"It is settled law that third parties must pay for the rights to transmit performances of copyrighted works to the public," Clement wrote.

But, Aereo lawyers say they aren't "performing" any protected work, they're just providing subscribers with a way to watch publicly-available broadcasts.

The lawyers point to a 1984 Supreme Court decision, Sony v. Universal Studios. The decision said that TV viewers can make a copy of copyright-protected programming on a video recording device. The court ruled that having a personal copy of a free-of-charge program over public airwaves does not violate the broadcast company's copyright.

Aereo feels this is the same principle in their case.

"Because Aereo's technology cannot be used to transmit content other than from a user's personal recording, it does not transmit the performance embodied in petitioners' broadcasts," Washington Appellate Lawyer David Frederick writes.

When cable and satellite companies came into business, they agreed to pay broadcast companies a "re-transmission fee" to offer these normally free channels on their pay-per-month services.

Next came Internet TV. Just like cable and satellite companies, these Internet TV companies paid the re-transmission fee to broascast companies. But Aereo is not paying this fee.

Aereo believes it is providing the same service as as antenna TV, and antenna TV is free. Only with Aereo, customers don't need an antenna or a TV, they get their programming through digital airwaves and on their computers, phones or tablets.

Still, broadcasters think Aereo is stealing their matieral.

"If Aereo prevails, nothing will stop other services that currently pay for the rights to retransmit broadcast television from devising their own Aereo-like workarounds to achieve the same result," Clements said.

Professional sports leagues have long warned viewers against re-broadcasting their content. A service like Aereo would likely anger these leagues as well.

Aereo is gaining support from Internet and cable groups.

This key case in TV's future is American Broadcastin Companies v. Aereo (13-461).