The lawsuit filed in Maricopa County Superior Court Wednesday seeks to overturn parts of the law allowing corporations and some nonprofits to avoid disclosure. It also seeks to invalidate provisions removing the Citizens Clean Elections Commission from enforcement authority over outside campaign spending.
A group of Democratic lawmakers, a union and a voter advocacy group are challenging a 2016 Arizona law that expanded the ability of some groups to spend unlimited amounts of money on elections without disclosing their donors.
The lawsuit says they violate the state Constitution because they illegally change the 1998 Clean Elections Act.
The provisions were part of a massive rewrite of campaign finance laws pushed by Secretary of State Michele Reagan last year. Reagan spokesman Matt Roberts says they're reviewing the lawsuit.