It would seem like a splitting of hairs, but then so much of copyright and trademark law is just that.

Cablevision came up with a system allowing its customers to record TV shows, as they might with a DVR, but store them remotely on a Cablevision server.

TV networks, which are generally opposed to all things DVR, objected and filed a lawsuit, arguing that Cablevision's remote DVR storage system violated their copyright protection of the shows they produce--and in a way that a TiVo device or similar home DVR device does not.

The networks, including CNN, CBS and Fox Networks Group, along with the Motion Picture Association of America, won the first round in federal court but then lost on appeal, when last August the U.S. Court of Appeals for the Second Circuit overturned the lower court's decision.

Yesterday the networks lost again when the U.S. Supreme Court declined to hear the case.

The effect is to enable Cablevision and other cable systems to broaden their offerings to consumers, allowing them to record and store programs without having to buy a home DVR device.

The networks worry that thus enabled, more and more viewers will use the service with the intent of zipping though ads on the recorded shows as they might with a TiVo device. About a third of homes now have some sort of DVR device.

Cablevision halted the rollout of its remote DVR service three years ago but now plans to introduce a version of it this summer, and presumably other cable systems will follow.

The network's beef with the remote system is that in effect it empowers a third party, the cable operator, to become a distributor of content that belongs to the networks. By contrast, the home DVR-recorded show is clearly for personal use and as such is not for distribution.

In any case, as copyright holders, the networks must be diligent in bringing legal challenges whenever they believe their copyright protection is being challenged, lest they open a floodgate of similar incursions.

And it becomes all the more critical as more and more content goes online or is offered on demand.

But they have a practical aim as well. Their long-term intent is to reach terms with cable systems such as Cablevision to restrict the ease with which users are enabled to skip ads.

What effect all this will have on ad-skipping is hard to say.

Numerous studies have been done on DVR usage and ad-skipping, and a number have concluded it occurs far less often than one might expect.

More to the point though, to skip an ad using a DVR device requires watching the ad as it’s speeded through to know when the program resumes. The effect is that the skipped ad gets more attention than if the viewer simply left the room.