Last week California Gov. Gavin Newsom (D) signed a bill (SB 27), passed on a straight party-line vote by the state’s Democrat-controlled Legislature, that requires candidates for President of the United States and California Governor to disclose their federal income tax returns in order to appear on the state’s primary election ballot.

The measure was clearly directed at President Trump, who has resisted making his returns public.

“If he has nothing to hide, President Trump shouldn’t be afraid to give American voters what they want, a copy of his tax returns,” said Sen. Mike McGuire (D), who coauthored the bill with Sen. Scott Wiener (D). “We know that over 60 percent of Americans want the president to release his returns, just like every presidential candidate has done for the past 40 years.”

In signing the bill, Newsome said in a statement: “As one of the largest economies in the world and home to one in nine Americans eligible to vote, California has a special responsibility to require this information of presidential and gubernatorial candidates.”

The governor went on to say that the U.S. Constitution “grants states the authority to determine how their electors are chosen, and California is well within its constitutional right to include this requirement.” But there’s some disagreement among legal experts about whether that’s actually the case.

The U.S. Supreme Court ruled in U.S. Term Limits Inc. vs. Thornton (1995) that states can’t impose qualifications on congressional candidates that are stricter than those specified by the Constitution, and some say that decision could also apply to presidential candidates.

But Erwin Chemerinsky, dean of the University of California, Berkeley’s law school, said the state law at issue in the 1995 case completely denied ballot access to U.S. House candidates who had already served three terms and U.S. Senate candidates who had already served two terms, while California’s new law imposes a requirement for ballot access “that can be easily met.”

And Adam Winkler, a professor of constitutional law at the University of California, Los Angeles, said, “The Supreme Court has repeatedly and emphatically upheld disclosure requirements, saying the interest in having voters informed justifies the burden on candidates.”

Douglas W. Kmiec, professor emeritus at Pepperdine Law School, appeared inclined to agree about the California law’s constitutionality, “given the unqualified power of the state legislatures to determine the method by which electors to the electoral college are chosen.” But he also said it was difficult to predict how the court would ultimately rule, and the law’s prospects might be better if it didn’t take effect until after the 2020 election.

“Applying it beforehand gives it a rather distinct anti-Trump frame of reference that the court could find objectionable,” he said.

Others were more firmly in the SB 27-is-unconstitutional camp.

“California can’t come along and say to get on the ballot, you have to disclose your tax returns,” said Theodore B. Olson, an attorney who has frequently argued before the Supreme Court. “And then Iowa might say you have to disclose records of domestic [litigation] with an ex-wife, and Alabama might say you have to disclose whether you have any illegitimate children.”

Gene Schaerr, another lawyer who has argued before the high court, said federal law protects the confidentiality of income tax returns, and California can’t force candidates to waive their rights under that law.

Jan W. Baran, an attorney in Washington, D.C. who’s practiced law for over 40 years, said California can’t create tax disclosure requirements for candidates for federal office.

“We can amend the U.S. Constitution to require candidates for president to disclose their income tax returns, but you can’t do it by passing a single state law,” he said.

David Keating, president of the Institute for Free Speech, meanwhile, said President Trump could just run as a write-in candidate in California or skip the state altogether, since he’ll probably have enough electors to secure his party’s nomination without the support of California’s. (LOS ANGELES TIMES, GOVERNING, CALIFORNIA GOVERNOR’S OFFICE, CALIFORNIA SENATE)