They're suing Kamala Harris (recently elected CA senator who was the CA Attorney General).
"IMDb shares the worthy goal of preventing age discrimination. But AB 1687 is an unconstitutional law that does not advance, much less achieve, that goal. To the contrary, rather than passing laws designed to address the root problem of age discrimination, the State of California has chosen to chill free speech and undermine public access to factual information.
"IMDb routinely and gladly updates information on IMDb.com in order to correct verified inaccuracies. But it has always been IMDb’s policy not to alter or delete any accurate factual information on the public website. Being compelled to do so not only violates basic free speech principles, but undermines the accuracy and reliability of the IMDb.com database on which millions of users rely.
"IMDb has empowered IMDbPro subscribers to remove their age information from IMDbPro if they are concerned that such information might affect casting decisions. AB 1687 does not merely violate the First Amendment rights of IMDb and its hundreds of millions of users and contributors. The statute also violates the Commerce Clause because California is attempting to police the internet far beyond the state’s own borders. And the statute separately violates federal law because it imposes liability on IMDb based on factual content that is lawfully posted by its users."
tldr; they're trying to argue that the current law is unconstitutional