Mozilla has filed its legal brief against the Federal Communications Commission (FCC), accusing the telecoms regulator of abdicating its role, ignoring public comments and failing to understand how the internet actually works.

The lawsuit is one of several ranged against the FCC for its controversial decision to tear up existing net neutrality rules. But while other lawsuits are based on the FCC's authority or relatively arcane legal issues, Mozilla's case is blunter: the FCC is doing a terrible job.

"For the first time in the history of the public internet, the FCC has disavowed interest and authority to protect users from ISPs, who have both the incentives and means to interfere with how we access online content," the organization argued in a blog post on Monday.

"The FCC needs to accept statutory responsibility in protecting those user rights - a responsibility that every previous FCC has supported until now," it argues, continuing: "That's why we’re suing to stop them from abdicating their regulatory role in protecting the qualities that have made the internet the most important communications platform in history."

The full legal brief has not yet been published but Mozilla characterizes it in the form of three main arguments:

The order to scrap existing net neutrality rules "fundamentally mischaracterizes how internet access works" – by effectively arguing that it is not possible for an ISP to provide website access without some degree of interference. Nonsense, says Mozilla.

The FCC has "completely renounced" its critical role of enforcer, Mozilla claims. Its latest order shoves internet access issues over to the FTC – which has itself been subject to a legal challenge that it doesn't have authority. Mozilla says only Congress can do that – not a regulator itself.

The FCC failed to carry out a "reasoned decision making" process by "ignoring much of the public record as well as their own data showing that consumers lack competitive choices for internet access." There is no shortage of evidence that the public comment process was a farce of the highest order, or that the internet access market in the US is a mess.

In addition to its filing, a number of other tech organizations will be filing support briefs on behalf of Mozilla, it said.

Mozilla says the reason for its lawsuit is to "defend users’ access to the internet without interference from gatekeepers" and argues that it is "imperative that all internet traffic be treated equally, without discrimination against content or type of traffic."

The case – 18-1051 [PDF] in front the Washington DC Court of Appeals – should proceed to oral arguments some time in November with a decision likely in early 2019. ®