SACRAMENTO, Calif. (CN) – California Gov. Jerry Brown has signed a bill to require clear disclosure of political contributors to print, television and online ads, a bill that far surpasses requirements under federal law.

Assembly Speaker Pro tem Kevin Mullin, D- South San Francisco, wrote the Assembly Bill 249, carrying on similar efforts by former Assemblyman Jimmy Gomez, who was elected to Congress last year.

“No more fine print,” Mullin said in a statement. “California voters will now be able to make informed decisions, based on honest information about who the true funders are of campaign ads. This transparency is critical to our democracy and I am proud that California has taken this historic first step to shine the light on ‘dark money.’ Hopefully this will encourage others to follow suit.”

Proponents say campaign spending increased by over $1 billion between 2012 and 2016, fueled by the U.S. Supreme Court’s ruling in Citizens United vs. FEC. The 2010 ruling affirmed the right of corporations to make independent contributions to political candidates and is credited with the creation of super PACs – politically motivated groups that cannot contribute to candidates or campaigns, but have unlimited spending limits for advertisement.

CA Common Cause also advocated strongly for the bill. “Every voter has a right to know who is trying to influence our votes and our Legislature,” said Nicolas Heidorn, the group’s legislative affairs director, in a statement. “While Congress and federal agencies fail to act to require more transparency in the post-Citizens United era, the Disclose Act will continue California’s leadership in building a strong and transparent democracy.”

The act saw a great deal of grassroots support, activism that helped propel the legislation through the process after other similar measures had failed.

“With the quiet gesture of a signature, Gov. Brown has loudly proclaimed California to be the national leader on the most important issue of our era: taking our democracy back from the special interests and restoring it to the people,” said Trent Lange, president of the California Clean Money Campaign, after Brown signed the bill on Saturday. “Every American who cares about democracy owes Gov. Brown, Assembly Speaker Pro tem Kevin Mullin, and all the bold leaders in the California Legislature of both parties who helped AB 249 pass an enduring debt of gratitude.”

The law makes changes to the way in which financial contributors are required to be displayed in advertisements. Campaign ads paid for by a committee that is not affiliated with a campaign must now declare who the top contributors are in clear and legible print, or in a clear, spoken voice in audio ads. Digital content will include the text “Who funded this ad?” and will link to a website disclosing the true donors.

Separate rules will govern donations made by campaigns or committees representing candidates. The law further specifies that changes to the top donors must also be disclosed. The law sets some standards for the size, color and readability of the disclosure information whether for print or digital advertisement and sets minimum lengths of time allowed to disclose information on audio ads.

The Howard Jarvis Taxpayers Association sent a letter of opposition to the bill while it was being heard by the state Senate. The watchdog group believes the measure overly restricts the freedom of political speech of donors and sets different rules for “preferred groups,” namely labor unions.

In its letter, the group said “there yet remains a point at which regulations designed to improve democracy actually impede it. This problem still exists in AB 249.”