James Grimmelmann walks a layman through the intricacies of copyright law in his article Why Johnny can’t stream: How video copyright went insane:

Suppose I could offer you a choice of two technologies for watching TV online. Behind Door Number One sits a free-to-watch service that uses off-the-shelf technology and that buffers just enough of each show to put the live stream on the Internet. Behind Door Number Two lies a subscription service that requires custom-designed hardware and makes dozens of copies of each show. Which sounds easier to build—and to use? More importantly, which is more likely to be legal?

If you went with Door Number One, then you are a sane person, untainted by the depravity of modern copyright law. But you are also wrong. The company behind Door Number One, iCraveTV, was enjoined out of existence a decade ago. The company behind Door Number Two, Aereo, just survived its first round in court and is still going strong.

The difference between them—and the reason for Aereo’s willfully perverse design—originated in a critical 2008 DVR decision by the federal Second Circuit Court of Appeals in Cartoon Network v. CSC Holdings (which everyone just calls “Cablevision”). The tech at issue in Cablevision was a “DVR in the cloud,” and because of the way the Second Circuit answered the question of whether a DVR “performs” a copyrighted TV show when the user hits “play,” the decision opened a whole range of possibilities for entrepreneurs willing to mash up technologies in ways God never intended.

This is the story of Cablevision, the companies that followed in its wake, and how we got to the strange place where wasting resources on thousands of tiny antennas made you legal—but where using one antenna broke the law.

What follows is a detailed explanation on why deploying 10,000 tiny antennas makes no technical sense—but the law demands it. The column concludes:

Perhaps we can think about the problem of copyright on the Internet another way. Instead of asking which back-end technologies are legal, it might make more sense to ask what it is legal for users to do with computers on the front end. This approach would let people spend less time worrying about the exact definitions of “reproduction” and “performance” and more time thinking about users’ rights, especially under fair use.

Cablevision itself illustrates what might have been. The whole point of the RS-DVR was that it was a perfect substitute for a home DVR. Reasoning by analogy, then, we might say that the two ought to either both be legal or both be illegal. And since home DVRs seem here to stay, it ought to be permissible for Cablevision to offer its customers exactly the same service they could have gotten by buying a gizmo. Call it “noninfringing personal fair use” and we can all go home.

The strangest thing about Cablevision is that the court didn’t even get a chance consider that argument. The parties agreed not to litigate the fair use issue. Yes, you read that right. It was a quid pro quo: Cablevision didn’t invoke users’ fair use rights and the cable networks didn’t try to holdCablevision liable for users’ infringements. That turned a case about users’ uses into a case aboutCablevision‘s technologies, changing a common sense debate over how far viewers can go in storing TV programs and watching them later into an abstruse legal disputation over the minutiae of primary ingest buffers and chains of transmission.

Another way of thinking about the decision is that the court wanted to provide a fair use ruling for viewers but wasn’t given the option, so it settled for much narrower rulings on the technologies involved.

Copyrighted content is the nuclear fuel of the Internet. It powers high-energy innovation, but can cause catastrophic legal meltdown if mishandled. Prolonged exposure has been scientifically proven to cause business-model mutations. Cablevision gave risk-tolerant entrepreneurs an inanimate carbon rod: enough to save the day for some of them, but hardly a long-term solution.