Trade organizations representing the nation’s biggest Internet providers today sued California to halt the state’s new net neutrality law.

The American Cable Association, the wireless industry’s trade group (CTIA), the Internet and television association (NCTA) and the broadband association (USTelecom) jointly filed suit in federal district court in California, calling the new law “a classic example of unconstitutional state regulation.”

The Internet providers argue that California’s net neutrality law was designed to undermine federal law by restoring the Obama-era regulations that the FCC repealed earlier this year. They argue that the federal Communications Act of 1934 expressly prohibits states from regulating services like Internet access that cross state boundaries.

“As the FCC has repeatedly recognized, due to the inherently interstate nature of Internet service, it is impossible or impracticable for an Internet service provider (“ISP”) offering BIAS to distinguish traffic that moves only within California from traffic that crosses state borders,” the trade groups argue in court documents.

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The industry groups joined with the Trump Administration in attempting to prevent the new law from taking effect. The Justice Department sued California within hours of Gov. Jerry Brown signing the bill into law on Sunday

California enacted the strongest net-neutrality provisions in the nation. The law restored old net neutrality rules the FCC abolished, which forbid Internet providers from blocking legal websites, intentionally slowing down Internet traffic or demanding fees for faster service.

It also goes further and prohibits a practice called “zero rating,” plans that allow a wireless subscriber to watch certain content without it counting against their monthly data cap. That’s a clever way for companies like, say, AT&T, to advantage its own service (say, the DirecTV Now service) over a competitor’s.

The trade groups argue that California simply can’t contravene federal law in this way. They argue it would create a headache for Internet providers, which would be forced to comply with a patchwork of potentially conflicting state and local regulations.

“This is already happening; while California has been at the forefront of these efforts, several other states have adopted or are in the process of adopting different and incongruous net neutrality requirements, which are consistent only in their disregard for the primacy of federal law,” the trade groups argue.

The Internet providers also argue California’s new net neutrality laws mess with interstate commerce. They ask the federal judge to prevent the new regulations from taking effect, because they violate the commerce clause and are pre-empted by federal law.

Consumer advocates were less than pleased with this development.

“Big telecom companies hate the California net neutrality bill because it prevents them from screwing over their customers more than they already do,” said Evan Greer, deputy director of Fight for the Future, which was active in passing the new state law. “It’s no surprise that they’re suing, but it does make it even more blatant and clear that [Attorney General] Jeff Sessions and [FCC Chairman] Ajit Pai are working directly on behalf of Big Cable in trying to block basic consumer protection legislation that passed with overwhelming bipartisan support.”