Aereo is a New York based startup that allows people to pay for their service and then receive clear streams of live broadcast television stations on their smart phone, tablet, computer or other connected device and record them. The company has been fighting lawsuits tooth and nail against the major networks, and for the most part winning.

Aereo charges $8 a month for it’s service. They use antennas that they have set up to take in a network station and rebroadcast it. Cable and satellite providers pay billions of dollars a year to have the rights to broadcast NBC, ABC, CBS and Fox. Aereo pays nothing, reports the Huffington Post.

In a court case brought on by Boston TV station WCVB the judge ruled that Aereo was not causing irreparable harm to the tv station and therefore could continue operating. When that ruling was handed down last month Aereo CEO Chet Kanojia said “Today’s decision makes clear that that there is no reason that consumers should be limited to 1950s technology to access over-the-air broadcast television,”.

Now both the National Football League (NFL) and Major League Baseball (MLB) have stepped in and filed an amicus brief with the Supreme Court. In the brief, both interests basically say that if Aereo is allowed to continue operating they will have no choice but to take their broadcasts to cable only pay television.

GigOM obtained the legal document on Monday afternoon which states:

If copyright holders lose their exclusive retransmission licensing rights and the substantial benefits derived from those rights when they place programming on broadcast stations, those stations will become less attractive mediums for distributing copyrighted content. The option for copyright holders will be to move that content to paid cable networks (such as ESPN and TNT) where Aereo-like services cannot hijack and exploit their programming without authorization.

Both the NFL and MLB feel that Aereo is undercutting the values of the deals they do with local television stations. In addition to network coverage stations themselves pay a small percentage to sell local advertising units within the broadcast of the game. The NFL and MLB also have lucrative online streaming deals with app vendors and cell phone carriers like Verizon (NFL), if Aereo takes off then there would be no reason for people to pay for premium apps to watch broadcasts of games.

Specifically the leagues are looking for the Supreme Court to overturn a ruling laid down in New York citing that Aereo is breaking copyright laws. Aereo service is done by markets. GigaOm reports that west coast courts haven’t been as friendly to Aereo as their east coast counterparts. For instance, in California Aereo like services are illegal.