A Washington state judge on Wednesday fined Facebook parent company Meta nearly 25 million US dollars (£21 million) for repeatedly and intentionally violating campaign finance disclosure law, in what is believed to be the largest campaign finance penalty in US history.

The penalty issued by King County Superior Court Judge Douglass North was the maximum allowed for more than 800 violations of Washington’s Fair Campaign Practices Act, passed by voters in 1972 and later strengthened by the Legislature.

Washington attorney general Bob Ferguson argued that the maximum was appropriate considering his office previously sued Facebook in 2018 for violating the same law.

Meta, based in Menlo Park, California, did not immediately respond to an email seeking comment.

Washington’s transparency law requires ad sellers such as Meta to keep and make public the names and addresses of those who buy political ads, the target of such ads, how the ads were paid for and the total number of views of each ad.

Ad sellers must provide the information to anyone who asks for it. Television stations and newspapers have complied with the law for decades.

But Meta has repeatedly objected to the requirements, arguing unsuccessfully in court that the law is unconstitutional because it “unduly burdens political speech” and is “virtually impossible to fully comply with.”

While Facebook does keep an archive of political ads that run on the platform, the archive does not disclose all the information required under Washington’s law.

“I have one word for Facebook’s conduct in this case – arrogance,” Mr Ferguson said in a news release. “It intentionally disregarded Washington’s election transparency laws.

“But that wasn’t enough. Facebook argued in court that those laws should be declared unconstitutional. That’s breathtaking. Where’s the corporate responsibility?”

In 2018, following Mr Ferguson’s first lawsuit, Facebook agreed to pay 238,000 US dollars (£205,000) and committed to transparency in campaign finance and political advertising.

It subsequently said it would stop selling political ads in the state rather than comply with the requirements.

Nevertheless, the company continued selling political ads, and Mr Ferguson sued again in 2020.

“Meta was aware that its announced ban would not, and did not, stop all such advertising from continuing to be displayed on its platform,” judge North wrote last month in finding that Meta violation’s were intentional.

Judge North fined Meta 30,000 US dollars (£25,000) for each of its 822 violations — about 24.7 million US dollars (£21.3 million). Ferguson described the fine as the largest campaign finance-related penalty ever issued in the US.

Meta, one of the world’s richest companies, reported quarterly earnings on Wednesday of 4.4 billion US dollars (£3.8 billion) on revenue of nearly 28 billion US dollars (£24 billion), in the three-month period that ended on September. 30.