Buried in the fine print of the FCC’s proposed Net Neutrality rules is a potential loophole that if left open would undermine the future of Internet freedom.

So says a group of prominent law professors who on Monday told the FCC that its proposed rules don't sufficiently define what the agency means by its use of the terms "non-discrimination" and "reasonable network management."

The professors -- all longtime champions of an open Internet – submitted a letter to the agency "to flag what we believe are two ambiguities in the Notice that we hope can be addressed early to provide a clearer foundation for comments."

"This is a historic rule and this letter was in the spirit of looking at other FCCs and creating a stronger rule that sets a policy that lasts longer as opposed to something that is highly dependent on the whims of a commission in power," Columbia law professor and Free Press board chair Tim Wu told the Washington Post after submitting the letter.

Wu's co-authors include Stanford Law Professor Barbara van Shewick, Harvard Law Professor Larry Lessig, Yale Law School's Jack Balkin, South Texas College of Law Professor John Blevins and University of Louisville School of Law's Jim Chen.

The professors are concerned with the contradictory and unclear definitions of key terms that are at the heart of the proposed Net Neutrality rules.

Without clear and reliable definitions of "non-discrimination" and "reasonable network management," we could see the types of blocking that occurred in 2007 when Comcast secretly barred customers from using file-sharing applications such as BitTorrent.

Allowing ISPs this much leeway would effectively eliminate Net Neutrality. The rules need to be unambiguous and strong, the scholars write. And even now, at the beginning of the process, the FCC should be clear as to what it believes the standards should be.

"Non-discrimination has been a central concept in telecommunications law and policy for nearly a century. The definition of non-discrimination will therefore be central to the operation of the rule and in particular its ‘fifth principle,’" the professors write, referring to FCC Chairman Julius Genachowski’s proposed fifth principle of nondiscrimination, which would support the four principles of the "Internet Policy Statement" promulgated by Genachowski’s predecessors Michael Powell and Kevin Martin.

The professors raise questions over language in the proposed rules "that seems surprisingly narrow – to a degree that makes it unclear that the result could accurately be called a nondiscrimination principle."

While we’re only at the beginning of the rulemaking process, it’s critical that the FCC understand that any ruling without strong nondiscriminatory provisions would undercut Net Neutrality’s main purpose: to keep control over Internet content in the hands of Internet users.

"We firmly believe that Chairman Genachowski intends to deliver a strong Net Neutrality rule to the public next spring," said Free Press Policy Director Ben Scott. "The ambiguities highlighted here may have been unintentional, and public interest advocates are committed to working with the agency to get clarity on these key issues as we work through the process."

On Monday, Free Press submitted to the FCC a policy brief that raised similar points in analysis of the entire language of the proposed rulemaking. The brief was delivered as a follow-up to a Friday meeting with Commissioner Michael Copps, during which Free Press praised the overall direction of the proposal.