California Gov. Gavin Newsom signed a law in July that requires all presidential candidates on the state’s primary ballot to release their tax returns for the preceding five years. But a constitutional amendment passed by California voters in 1972 may prevent that law from being enforced.

The new law, SB 27, applies to all candidates, but was aimed at Trump, who has not yet released his tax returns. It would not prevent him from appearing on the general election ballot in California, but its backers argued that it would be an important precedent that could put new pressure on the president.

However, critics argued that the new law was unconstitutional, based on legal precedents that struck down extra requirements for the office of president that went further than the simple prescriptions in Article II of the U.S. Constitution.

In addition, the San Francisco Chronicle points out, there could be state constitutional provisions that bar the new law as well:

Forty-seven years ago, California’s voters opened the state’s presidential primaries to all nationally recognized candidates. … [I]n 1972, 61% of the state’s voters approved Proposition 4, a state constitutional amendment, which said the presidential primary ballot must list “recognized candidates throughout the nation or throughout California,” as determined by the secretary of state.

Secretary of State Alex Padilla — whose tenure has been marred by mismanagement of “motor voter” registration through the Department of Motor Vehicles — argues that he has the discretion to determine who the “recognized candidates” are.

The California Supreme Court will hear arguments from Padilla, and from Republicans challenging the law, later this month.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He earned an A.B. in Social Studies and Environmental Science and Public Policy from Harvard College, and a J.D. from Harvard Law School. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. He is also the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.