The US Congress still needs to deal with network neutrality, and supporters in Congress are willing to block any legislation favoured by broadband providers until the issue is resolved, a leading Democratic lawmaker said on Wednesday.

"Network neutrality is a large, unresolved debate," said representative Rick Boucher, a Virginia Democrat, speaking at the State of the 'Net Conference in Washington DC. "It's the internet's open and accessible policy that has enabled it to be a platform of innovation."

A net neutrality law, which would prohibit broadband providers from blocking or slowing web content from competitors, stalled in Congress in 2006, and large broadband providers such as AT&T and Verizon opposed efforts to pass a law. But net neutrality advocates — many of them part of the Democratic majority that now controls both houses of Congress — would block any legislation requested by the large broadband providers until a net neutrality compromise is hammered out, Boucher predicted.

Last year, AT&T and Verizon pushed for a new law that would streamline the franchising process they must go through to offer television over IP (Internet Protocol) service in competition with cable TV. But this year, the large broadband providers have largely backed off on their lobbying efforts, and Boucher suggested that's because Democrats will demand a net neutrality law as a trade-off for any legislation that benefits providers.

Boucher supports a net neutrality law, but he called for compromise. Congress should not pass a net neutrality law with "unintended consequences" that hurt the development of the internet, he said. "I don't want to do anything that has the effect of hobbling innovation inside the network," he added.

Other speakers at the conference, sponsored by the bipartisan Advisory Committee to the Congressional Internet Caucus, suggested a net neutrality law would hurt efforts to increase broadband adoption in the US. A net neutrality law would limit broadband providers' options for providing new services, said George Ford, chief economist at the Phoenix Center for Advanced Legal and Economic Public Policy Studies, a free-market-focused think tank.

"We should exercise discipline," Ford said. "We rarely do that with communications policy."

Other speakers argued there's little evidence of broadband providers blocking competitors' web content, a scenario net neutrality advocates want to prevent. "Economic change and technological change needs room to breathe," said Christopher Yoo, a tech law professor at Vanderbilt University.

If broadband providers eventually take action that harms customers and competition, then Congress should pass a law, Yoo said.

Yoo and David Farber, a computer science professor at Carnegie Mellon University, argued that broadband providers need the ability to block internet content such as spam and to shut down web applications that hog bandwidth. Providers should also be allowed to prioritise web applications such as video or voice, allowing customers to have a high quality of service, Farber said.

"If you try to get quality of service for everyone, you don't get quality of service," Farber said.

But Tim Wu, a professor at Columbia University Law School, said providers should only block content in the most extreme circumstances. The difference between "good blocking" and "bad blocking" depends on the user's perspective, he said.

"Blocking should be highly suspect," Wu added. "We say good blocking is good and bad blocking is bad, but so does the Chinese government. They're making bad decisions at the centre [of the network]."