Cal. Elec. Code § 6881
The Legislature finds and declares that the State of California has a strong interest in ensuring that its voters make informed, educated choices in the voting booth. To this end, the state has mandated that extensive amounts of information be provided to voters, including county and state voter information guides. The Legislature also finds and declares that a Presidential candidate's income tax returns provide voters with essential information regarding the candidate's potential conflicts of interest, business dealings, financial status, and charitable donations. The information in tax returns therefore helps voters to make a more informed decision. The Legislature further finds and declares that as one of the largest centers of economic activity in the world, the State of California has a special interest in the President refraining from corrupt or self-enriching behaviors while in office. The people of California can better estimate the risks of any given Presidential candidate engaging in corruption or the appearance of corruption if they have access to candidates' tax returns. Finally, the State of California has an interest in ensuring that any violations of the Foreign Emoluments Clause of the United States Constitution or statutory prohibitions on behavior such as insider trading are detected and punished. Mandated disclosure of Presidential candidates' tax returns will enable enforcement of the laws against whichever candidate is elected President. The Legislature finds and declares that compliance costs with this requirement will be trivial.
Ca. Elec. Code § 6881