ABC, CBS, Fox and NBC filed a 59-page brief to the Supreme Court a few weeks ago that detailed how online video startup Aereo is stealing their programming and undermining the TV business model. The filing also noted that “a ruling against Aereo would pose no threat to innovative online-distribution services such as Hulu, Netflix, and Amazon,” since those services “pay for the right to use copyrighted content.” In a Supreme Court filing yesterday, the Justice Department backed the networks in their fight with Aereo.

“Broadcasters argued that Aereo, which provides broadcast TV shows to subscribers over the Internet without paying licensing fees to stations, is violating federal copyright law designed to protect content creators and distributors,” reports Re/code. “Aereo has denied violating broadcasters’ copyrights through its unique online delivery system, although the company joined broadcasters in asking the Supreme Court to review the case.”

The networks have warned that an Aereo win could lead to dire consequences and significant changes to their current business model, including how they charge pay TV companies to retransmit broadcast signals. The National Football League and Major League Baseball have argued in support of the broadcasters.

“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 leagues stated in their own brief.

“Justice Department lawyers argued that Aereo’s broadcast television streaming service infringes on broadcasters’ copyrights and asked the court to reverse a lower court’s decision that found in favor of the startup,” explains Re/code in a related article.

“A decision rejecting [Aereo’s] infringing business model and reversing the judgment below need not call into question the legitimacy of innovative technologies that allow consumers to use the Internet to store, hear, and view their own lawfully acquired copies of copyrighted works,” said the Justice Department.

Aereo recently launched in Austin, Texas, and is currently offered in 10 metro areas. The Supreme Court is expected to issue a decision by June, following oral arguments scheduled for April 22.