First introduced in the late 1800s to save the strain on horses hauling carts up the city's steep inclines, the 15, 500-pound cable-powered cars grip a continuously moving underground cable with pliers-like gear to travel the streets of San Francisco.

NPR: San Francisco Cable Car Accidents Costs Millions

In her majority opinion, Judge Judith Rogers said the programmers' case faltered because they couldn't cite an example of a cable operator who isn't either already using all-digital operations or moving in that direction.

WSJ: Cable Must Air Broadcast Signals