Aereo isn’t going down without a fight. Not even close.

The controversial streaming TV service yesterday filed a 100-page Supreme Court opening brief to once again defend itself against major broadcasters’ claims that it’s violating the U.S. Copyright Act by letting its subscribers watch their live broadcast programming online.  

The Barry Diller-backed startup apparently isn’t afraid to take on the royalty-hungry media Goliath known as network TV’s Big Four -- ABC, CBS Broadcasting, NBCUniversal and Fox Television Studios. The networks want the Supreme Court to shut down Aereo, accusing the firm of outright stealing their copyrighted programming signals on a massive scale.

Related: In Aereo's Battle With Broadcasters, Justice Department Picks a Side

“Today, we filed our response brief, setting forth the basis for our steadfast conviction that Aereo’s cloud-based antenna and DVR technology falls squarely within the law,” Aereo founder and CEO Chet Kanojia said in a passionate letter addressed to subscribers released on his company’s blog yesterday. It was fittingly titled “Standing up for technology, innovation and progress.”

“We have every confidence that the Court will validate and preserve a consumer’s right to access local over-the-air television using an individual antenna, make a personal recording with a DVR, and watch that recording on a device of their choice,” said Kanojia. “We think you should be able to decide whether you use home equipment or whether you take advantage of the ease, convenience and lower cost of cloud-based equipment and storage.”

Aereo uses a sophisticated tiny antenna and cloud-based DVR system that lets subscribers watch live broadcast TV on their smartphones, tablets and internet-connected TVs.

Its investors, which have poured some $97 million into the 2-year-old company to date, seem to think the startup stands a decent chance against the broadcast TV giants, as it already has on three different occasions -- once in federal district court and twice in the Second Circuit Court of Appeals.  

Related: Aereo Just Raised $34 Million to Expand 50 Percent in Next 3 Months

Now the Supreme Court is scheduled to hear opening oral arguments on April 22 in the American Broadcasting Companies v. Aereo case, the outcome of which could spell sweeping changes -- or worse, the end -- not only for Aereo, but for fellow streaming media competitors like Crackle, Netflix and Amazon Prime. Perhaps not for Hulu, though. It’s owned by corporate mammoths NBCUniversal, 21st Century Fox and the Walt Disney Company.

Aereo, which offers subscriptions starting at $8 per month, is still streaming on during the good fight in several large American cities, including Atlanta, Austin, Baltimore, Boston, Cincinnati, Dallas, Detroit, Houston, Miami, New York and San Antonio. On its website, the company says it will expand to 16 more cities soon.

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