CTIA, which long fought against the FCC’s net neutrality regulations, may now find itself defending them in court.

The trade group today filed a motion to intervene in four lawsuits that claim the rules unfairly favor the wireless industry by not offering mobile broadband users the same protections as fixed broadband users.

The FCC imposed lighter restrictions on mobile broadband providers than fixed providers when it crafted its open Internet rules. The agency argued the distinction was necessary because “wireless is different,” an assertion now being challenged in court.

CTIA wants to help defend the FCC’s decision in four separate complaints filed by Free Press, the Media Mobilizing Project, Mountain Area Information Network and People’s Production House.

“CTIA wishes to defend the FCC against that challenge and any related arguments that the FCC erred in imposing too few regulatory burdens,” CTIA stated in documents filed with the U.S. Court of Appeals for the District of Columbia Circuit.

CTIA is not challenging Verizon’s lawsuit against the FCC’s net neutrality rules, which claims the FCC overstepped its authority in issuing the regulations. A CTIA spokeswoman declined to elaborate on the decision to exclude Verizon’s case from its motion, but Verizon claims the FCC overstepped its authority in issuing the regulations, not that they don’t go far enough.

“CTIA does not seek to intervene (in support of the FCC or otherwise) in Verizon v. Federal Communications Commission, Nos. 11-1355 and 11-1356, in which Verizon has challenged the FCC’s underlying statutory authority to adopt net neutrality rules for any class of broadband Internet access services,” the group said in its filing.

“It’s interesting the only time CTIA seems to think the FCC is right is when they’re not doing any regulating at all,” Free Press President Craig Aaron said in response to CTIA’s latest legal move.

Free Press argues the FCC’s open Internet rules should apply equally to both fixed and mobile broadband providers, instead of exempting wireless Internet providers from some of the most burdensome regulations.

The Media Access Project is representing Mountain Area Information Network, the Media Mobilizing Project and People’s Production House. Andrew Schwartzman, the nonprofit’s policy director, said CTIA’s move was not a surprise.

“We fully expected CTIA to join the case to support the FCC’s position,” Schwartzman said. “Our problem with what the FCC did is that it didn’t go far enough – it didn’t extend nondiscrimination to all aspects of wireless Internet service. CTIA won’t agree with that position.”

The Media Access Project is also representing Access Humbolt in its challenge to the FCC’s new Internet regulations. CTIA has not yet filed a motion to intervene in that case.

An FCC spokesman declined to comment on the matter. Mountain Area Information Network also declined to comment. Neither the Media Mobilizing Project nor the People’s Production could be immediately reached.

The net neutrality regulations will go into effect on Nov. 20. They are being challenged by a number of advocacy groups and telecommunications companies.

Under the rules, fixed broadband providers may not “unreasonably discriminate” against lawful network traffic; must disclose information about speeds and network management practices; and are barred from blocking lawful content, applications and devices that don’t harm the network.

Mobile broadband providers are subject to a less-stringent set of requirements comprising a transparency rule for speeds and network management and a basic ban on the blocking of lawful websites and competing services that is subject to “reasonable” network management.