CBS and FOX executives have already made the bold declaration that they will take their networks off the air and go cable-only if they are unsuccessful in their bid to crush streaming video service Aereo. Now two pro sports leagues have said they will leave the airwaves if Aereo can profit off of them without sharing.

Here’s the background for those late to the game: Aereo is a startup streaming service — currently only available in a handful of markets — that uses arrays of incredibly small antennae to capture networks’ over-the-air signals, sending them over the Internet to paying subscribers’ computers and wireless devices. Aereo claims that it does not need to pay retransmission fees to the networks because each individual antenna it uses is dedicated to a single subscriber. Thus, contends the company, it’s doing nothing more than providing subscribers’ with the equivalent of a rooftop antenna that picks up freely available network feeds.

The networks obviously disagree, calling it thievery and a violation of copyright. In each region Aereo has launched, it’s been sued in federal court, but so far the networks have been unable to convince any of the courts to issue a preliminary injunction stopping Aereo from offering service. The case seems destined to be heard by the Supreme Court.

Last week, Major League Baseball and the National Football League filed a brief with the Supremes to support the networks’ side of the case. The leagues claim that if Aereo wins in court, they will have to take their programming to basic cable.

“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,” reads the brief. “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.”

The big risk, claim the leagues, is the precedent that an Aereo victory would send. As we recently wrote, several cable operators — DirecTV, Time Warner Cable, Charter, among others — are currently developing their own Aereo-like technologies in the hopes of getting around the billions of dollars in retransmission fees paid to broadcasters each year. That would mean less money in the leagues’ coffers.

One specious argument made by the NFL states that Aereo or some similar service could create an NFL Sunday Ticket-like package simply by taking in all the various network feeds of live games and sending them on to subscribers without paying the league a dime. There’s a huge problem with that claim. Aereo’s success in the courtroom thus far has been tied to its one-antenna/one-subscriber setup, and the fact that this antenna is pulling in over-the-air feeds and providing them to a subscriber in the specific broadcast area they live in. Unless Aereo has developed a teeny antenna that can somehow gather every broadcast signal from Seattle to Miami, the described situation just isn’t going to happen.

We’ll have to wait and see if the NFL is trying to bluff about pulling its feeds from over-the-air broadcasts, as doing so could risk angering fans and significantly lowering its TV audience.

We don’t know why MLB is complaining so much about Aereo. In many markets, most MLB games are already on basic cable channels (often ones operated by huge broadcast and/or cable operators like Comcast and FOX), and even the majority of postseason baseball is now on TBS instead of the networks.

NFL, MLB To Supremes: If Aereo Wins, Broadcasters Lose [Multichannel.com via DSL Reports]

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