It’s tempting to conclude that the California law requiring candidates for President to release their tax returns will automatically have the same outcome as the 1995 case
U.S. Term Limits, Inc. v. Thornton, in which the Supreme Court held unconstitutional an Arkansas law prohibiting an otherwise-eligible candidate for Congress from appearing on the ballot if that candidate had already served three terms in the House of Representatives or two terms in the Senate.
The outcome in
Thornton was based on the Court’s conclusion that it is a fundamental principle of the constitution that the people are to choose their representatives to Congress. However, unlike the election of Congress the constitution did not put the election of the President into the hands of the people but rather put it into the hands of the state legislature: “[The President] shall...together with the Vice President, chosen for the same Term, be elected, as follows: Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors…” Accordingly, the Supreme Court pointed out in
Bush v Gore that “the state legislature’s power to select the manner for appointing electors is plenary; it may, if it so chooses, select the electors itself, which indeed was the manner used by state legislatures in several States for many years after the framing of our Constitution.” (The definition of “plenary” is “complete in every respect : ABSOLUTE, UNQUALIFIED.”)
(Much intelligent analyses redacted)