President Donald Trump sued California Tuesday challenging a state law that requires candidates for president to disclose income tax returns before they can appear on the state's primary ballot.
The federal lawsuit from Trump and his campaign is the latest move by the President to resist efforts to turn over his tax returns.
The law adds an "unconstitutional qualification" to the fixed set of qualifications for the presidency set forward in the Constitution and violates the First Amendment, Trump's lawyer William Consovoy argued in the lawsuit filed in the US District Court for the Eastern District of California.
California Democratic Gov. Gavin Newsom signed the state's "Presidential Tax Transparency and Accountability Act" last month. "The United States Constitution grants states the authority to determine how their electors are chosen, and California is well within its constitutional right to include this requirement," he said in a statement.
A second similar lawsuit was also filed Tuesday by Republican voters along with the Republican National Committee and the Republican Party of California who argue that this a political maneuver that takes voting rights away from Trump's supporters.
Newsom responded to the challenge on Tuesday.
"There's an easy fix Mr. President -- release your tax returns as you promised during the campaign and follow the precedent of every president since 1973," the California governor tweeted.
Legal expert Rick Hasen of the University of California, Irvine, said the state law is of "uncertain constitutionality."
"It is unclear whether state legislative power contained in Article II of the (US) Constitution gives California the power to take this step," he said adding that the law might infringe upon the rights of political parties to select nominees of their choice.
"If such a law is upheld as constitutional, we might see a race to the bottom whereby other states enact ballot access requirements, such as a requirement for candidates to produce a birth certificate, which could affect which candidates can run in which states," he added.
Trump's team of private lawyers has been on the offensive in recent weeks filing lawsuits to thwart attempts by Democrats to see his tax returns. They've filed a handful of lawsuits in federal courts across the country, mainly to stop House Democrats from seeking the tax returns through the Trump family and company's banks, an accounting firm or under a New York state law.
Trump has lost and appealed some of the court cases, but others, such as about the state laws, have not yet been decided.
Later Tuesday afternoon, the Justice Department may take a position for an appeals court on whether Trump can stop House Democrats from subpoenaing an accounting firm for his tax returns from when he was a private citizen, according to a court order.