The Trump administration is suing California in an effort to block the state’s new net neutrality law from going into effect.

California’s new law, set to take effect Jan. 1, bans Internet providers like Comcast and Verizon from blocking or slowing down websites or charging companies for faster delivery. It is widely viewed to be the toughest net neutrality law in the nation and puts the state at odds with the Federal Communications Commission (FCC), which repealed federal net neutrality regulations last year.

Justice Department officials contend in the complaint that the federal government, not the states, has exclusive authority to regulate the Internet. The DOJ challenge is likely to be merged with a separate lawsuit filed this week by the telecom industry.

“Not only is California’s Internet regulation law illegal, it also hurts consumers,” said FCC Chairman Ajit Pai. “The law prohibits many free-data plans, which allow consumers to stream video, music and the like exempt from any data limits. They have proven enormously popular in the marketplace, especially among lower-income Americans. But notwithstanding the consumer benefits, this state law bans them.”

California Attorney General Xavier Becerra said the lawsuit is coming from “power brokers” with “an obvious financial interest in maintaining their stronghold” over the Internet.

“California, the country’s economic engine, has the right to exercise its sovereign powers under the Constitution, and we will do everything we can to protect the right of our 40 million consumers to access information by defending a free and open Internet,” Becerra said.