Cal. Health and Safety Code § 33501.3

If an action specified in Section 33501 challenging the validity of any finding and determination that the project area is blighted is filed in any court, each party filing any pleading or brief with the court in that proceeding shall serve, within three days of the filing with the court, a copy of that pleading or brief on the Attorney General. Relief, temporary or permanent, shall not be granted to a party unless that party files proof with the court showing that it has complied with this section. A court may, by court order, allow a party to serve the Attorney General after the three-day period, but only upon showing of good cause for not complying with the three-day notice requirement, and that late service will not prejudice the Attorney General’s ability to review, and possibly participate in, the action.