A group of attorneys general for 21 states and the District of Columbia has sued to block the Federal Communications Commission's repeal of net-neutrality rules.
New York attorney general Eric Schneiderman, who is leading the suit, said Tuesday that the end of the net neutrality rules would hurt consumers and businesses.
Tech companies and public-interest groups are also expected to file suit or help with litigation against the repeal.
The FCC voted in December along party lines to reverse rules introduced in 2015 that barred internet service providers like AT&T, Comcast and Verizon from blocking or throttling traffic or offering paid fast lanes, also known as paid prioritization. The new rules will not take effect for several months, the FCC has said.
A group of the state attorneys general are arguing the FCC's action was "arbitrary, capricious and an abuse of discretion" and that it violated federal laws and regulations. An appeal may not be heard until the rules officially take effect.
A reversal of the FCC decision needs the approval of the Senate, the House of Representatives and President Donald Trump. Trump backed the FCC action, the White House said last month, and overturning a presidential veto requires a two-thirds vote of both chambers.
U.S. Senate Democrats said on Tuesday they had the backing of 50 members of the 100-person chamber to overturn the decision to reverse the net neutrality rules.
Senator Ed Markey said in a statement that all 49 Democrats backed the repeal. Earlier this month, Republican Senator Susan Collins said she would back the effort to overturn the FCC's move. Democrats need 51 votes to win any proposal in the Republican-controlled Senate because Vice President Mike Pence can break any tie.