US operators Verizon Communications and MetroPCS filed papers with a federal court this week challenging the Federal Communications Commission’s (FCC) efforts to lay down net neutrality rules.

In a complaint to the US Court of Appeals in Washington, the operators argue that the regulations are "arbitrary and capricious" and that the FCC acted “without statutory authority to insert itself into this crucial segment of the American economy.”

The FCC passed the net neutrality law in a tight vote in late December 2010 and it became enforceable from November last year. The legislation is seen as a compromise measure between protecting open Internet policies and allowing some operators – particularly mobile operators – the flexibility to support new content services. But critics argue that the lack of clarity has left the FCC open to legal challenges.

The same Washington court had earlier backed US cable operator Comcast in a challenge to the FCC’s position.

In this week’s filing, Verizon and MetroPCS argue that, instead of "proceeding with caution" following the Comcast ruling, the FCC decided to “go even farther… and impose dramatic new restrictions on broadband Internet access service providers."

The operators’ position is based on constitutional grounds, claiming the regulations violate free speech: “Broadband networks are the modern-day microphone by which their owners engage in First Amendment speech," they argued. 

"We look forward to defending our open Internet rules in court," FCC spokesman Neil Grace told Bloomberg. "This strong and balanced framework is helping ensure that the Internet continues to thrive as an engine for innovation, investment, job creation, and free expression."