Three legal veterans on Tuesday backed newly signed state legislation that would require President Donald Trump, and any other presidential candidate, to disclose their income tax returns in order to appear on California's 2020 ballot.

Boies Schiller Flexner chairman David Boies; Gibson, Dunn & Crutcher partner Theodore Boutrous Jr.; and UC Berkeley School of Law Dean Erwin Chemerinsky all supplied short opinions asserting the constitutionality of the new law in a media release from Gov. Gavin Newsom's office.

The new law “does not keep any candidate from being on the ballot so long as he or she complies with a simple requirement that is meant to provide California voters crucial information,” Chemerinsky wrote. “This is the state acting to make sure that its voters have information that might be very important to them when they cast their ballots as to who they want to be President of the United States.”

Jay Sekulow, a lawyer for Trump, said in a statement that “the State of California's attempt to circumvent the Constitution will be answered in court.”

Boutrous and Chemerinsky are outspoken critics of the Trump administration, writing and speaking regularly about what they and other observers contend are violations of norms and the rule of law. In January, Boies delivered a speech in New York in which he said Trump had made statements about federal judges that undermined the independence of the judiciary.

Chemerinsky told The Recorder he was contacted by a representative from the governor's office about opining on the constitutionality of the new state law. “I would gladly defend this law in court, though the state has its attorney general to do that,” Chemerinsky said.

Boies said the Constitution gives states authority to decide how their electors are chosen.

“No other constitutional provision is implicated or violated by a state's requirement that a Presidential candidate disclose tax returns,” Boies said in his statement. “Moreover, California, which permits electors to be chosen by popular vote, has an important interest in insuring that its voters are informed.”

He noted that the production of tax records can be part of some civil litigation, and obtaining a bank loan.

Boutrous, a Gibson, Dunn & Crutcher partner in Los Angeles and co-chairman of the firm's litigation group, pointed to the U.S. Court of Appeals for the Ninth Circuit's opinion this month in De La Fuente v. Padilla, which upheld a California state law requiring independent candidates to collect signatures from 1% of registered voters to appear on a statewide ballot.

“As the Ninth Circuit recently explained, such laws are constitutional if they are 'generally applicable, even-handed, [and] politically neutral,' and the state has an important justification for enacting the law,” Boutrous said in Newsom's press release. “Here, California's bill meets all of these requirements. It will apply to any candidate for President, whether Republican, Democrat, or Independent.”

The law, which requires five years of tax disclosures, also applies to future gubernatorial candidates. But the measure is clearly aimed at Trump, who has refused to make public his returns despite telling would-be voters in 2016 and beyond that he would “absolutely” release them. Trump claimed he could not release his tax returns because of an alleged IRS audit. But lawyers said even such an audit would not have barred disclosure.

“These are extraordinary times and states have a legal and moral duty to do everything in their power to ensure leaders seeking the highest offices meet minimal standards, and to restore public confidence,” Newsom said in a signing statement. “The disclosure required by this bill will shed light on conflicts of interest, self-dealing, or influence from domestic and foreign business interest.”

Then-Gov. Jerry Brown vetoed similar legislation two years ago. “Today we require tax returns, but what would be next?” Brown wrote in his veto message. “Five years of health records? A certified birth certificate? High school report cards? And will these requirements vary depending on which political party is in power?”

Trump recently sued New York and the House Ways and Means Committee to try to stop any release of his New York state tax returns. The suit, in Washington's federal trial court, challenges a new state law that permits New York authorities to disclose returns to the congressional committee.

Separately, the House Ways and Means Committee has sued the U.S. Treasury Department and IRS to obtain six years' worth of Trump federal tax returns. Federal law requires the IRS to furnish copies of federal returns on a request by the committee. Justice Department lawyers have failed to comply with the terms of a subpoena, and they argue the committee has no legislative purpose to obtain the records.