A Stanford law professor and net neutrality expert filed a report with the FCC claiming T-Mobile's (NYSE:TMUS) Binge On "harms competition, innovation and free speech" and is likely illegal.

In a 51-page document, Barbara van Schewick provided more than a half-dozen reasons why the zero-rated mobile video service "harms Internet openness" as defined by the FCC's Open Internet Order of 2015. The service enables T-Mobile to give some providers a competitive advantage by making Binge On video more attractive than other video because the service doesn't incur data charges, van Schewick noted. Similarly, it constrains consumer choice by enabling users to watch unlimited video from Binge On providers but not from their competitors.

The professor also said Binge On's technical requirements "categorically exclude providers like YouTube," which uses different protocols, and discriminate against providers that use encryption and other technologies. "Binge On allows some providers to join easily and creates lasting barriers for others, especially small players, non-commercial providers, and start-ups," she wrote. "As such, the program harms competition, user choice, free expression, and innovation."

T-Mobile has argued that those technical requirements are necessary for it to identify the content provider through Binge On, which allows the carrier to zero-rate the data generated by participating streaming video providers. A T-Mobile representative wasn't immediately available for comment on van Schewick's filing.

Binge On is similar to Music Freedom, T-Mobile's other zero-rated program that launched in 2014, van Schewick observed. And while Music Freedom has grown from seven to 40 providers, van Schewick alleges that some smaller services had to wait 18 months to be included, and that T-Mobile simply opted not to respond to others.

Finally, van Schewick claimed Binge On video is not actually unlimited because users can no longer watch it after reaching their monthly cap through other uses and applications. "T-Mobile's advertising misleads customers and likely violates the FCC's transparency rule," she wrote.

Binge On has clearly gained traction with some T-Mobile users -- the operator said yesterday that customers have watched 34 petabytes of video for no additional fee since Binge On launched -- but van Schewick is only the most recent to criticize the service on net neutrality grounds. The Electronic Frontier Foundation earlier this month reported that T-Mobile truly does slow transmission speeds of vide for Binge On users -- a claim the carrier had previously denied -- and YouTube has complained that the carrier downgrades its video content even though it isn't a Binge On provider.

The operator has responded by pointing to the fact that users can turn Binge On on and off at will, incurring data charges in exchange for higher transmission speeds and higher quality video. And T-Mobile yesterday said it had made it easier to turn the service on and off, decreasing the number of clicks required online and in its customer app.

T-Mobile has clearly attracted the attention of FCC Chairman Tom Wheeler, whose agency earlier this month had a "productive" meeting with T-Mobile and Comcast about their policies for zero-rated data, according to Ars Technica.

For more:

- see this van Schewick report (PDF)

Related articles:

T-Mobile: Customers have watched 34 petabytes of video for no additional fee since Binge On launch

EFF: T-Mobile's Binge On really is throttling video

YouTube complains about T-Mobile's Binge On as controversy over zero-rated data offerings heat up

FCC's Wheeler beckons AT&T, T-Mobile on mobile data policies

T-Mobile, AT&T and others draw scrutiny with zero-rated data

AT&T still 'very bullish' on Sponsored Data despite just 10 customers so far