Even the American Civil Liberties Union, which spoke out against the use of DPI in recent House Telecommunications Subcommittee hearings, concedes the technology has its value.

“We’re not Luddites here,” said Timothy Sparapani, ACLU senior legislative counsel. “We are not offended by the technology. It obviously has good applications. Preventing denial-of-service attacks, making sure authorized users on the system aren’t using bandwidth inappropriately. Those sorts of things make a lot of sense to me.”

What’s hard to reconcile, however, is the juxtaposition of the political dangers that DPI still seems to pose with the practical advantages it brings to bandwidth-constrained networks.

“A lot of people within the industry think it is inevitable, that network operators will get control at some point, and they are going to be able to use their visibility into the network and be able to do things with that information,” said IDC analyst Matt Davis. “The precedent is being set by Google and Yahoo! and all the portal vendors who have been profiling and collecting information on online activity. It is an easy logical move from having a cable operator know your video-on-demand choices to your online portal knowing your search choices to a facilities-based provider that has some of this information and can put it to use to deliver a better service.”

The only rational way to run the network, said Ovum Vice President Mark Seery, is to “create a relationship between usage and price and allow service providers to build an infrastructure that can deliver on its promises. That’s the natural direction, exactly how you implement it could be up for debate.”

So the issue for the telecom industry is to find a way to show the positive site of DPI and similar technologies to a potentially skeptical public and an already dubious set of politicians. That could be an uphill battle.

Rep. Edward Markey (D-Mass) and Rep. Joe Barton (R-Tex) of the House subcommittee already shot down one use case for DPI. NebuAd, the Silicon Valley startup, used DPI in a trial on the Charter Communications network to track user activity on the Internet and target advertising based on that activity. But NebuAd lost the Charter deal and could lose others with Embarq, CenturyTel and other ISPs. At the recent House Subcommittee on Telecommunications and the Internet hearing, NebuAd came under harsh criticism from Markey for not alerting consumers to this invasion of their privacy.