The last few weeks have been a rugged legal stretch for incumbent television companies.

First, an appeals court declined to rehear a case in which broadcasters sought to close down Aereo, a company that allows users to record and play back broadcast television over the Internet. And then last week, another appeals court declined to stop Dish Network, the satellite television company, from selling a service called Hopper, which lets viewers automatically skip ads.

The cases are far from settled, but the stakes could not be bigger. Broadcast television as we know it now stands on two legs: advertising and retransmission fees from cable providers. With Hopper skipping ads and Aereo allowing for distribution over the Internet without payment, profits might go dark.

But the legal cases also seem to defy a kind of common-sense logic: how can insurgents use programming created by someone else to their own ends without sharing revenue?

The answer could get very complicated, very fast, but let’s try to make it simple. The dawn of consumer-controlled television began with the clunky, whirring Sony Betamax in the 1970s. Networks and program providers didn’t like consumers making copies of their movies and TV shows, but a landmark Supreme Court case in 1984 held that taping and time-shifting on the part of viewers was “legitimate fair use.”