Emergency room doctor treats a coronavirus disease patient in a respiratory isolation room at Providence Mission Hospital in Mission Viejo, Calif., Jan. 27.

Photo: SHANNON STAPLETON/REUTERS

California Gov. Gavin Newsom made a splash this summer by running ads in Florida that claimed “freedom is under attack in your state.” The ads should have aired in his own state, which is the land of lockdowns and mask mandates. And under a new state law, doctors may even be punished for disputing the government’s public-health orthodoxy.

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These experts are often wrong and loath to admit it, as we learned with pandemic government lockdowns. Yet California Democrats last month enacted legislation that empowers the state medical board to discipline doctors licensed in the state who “disseminate misinformation or disinformation” that contradicts the “contemporary scientific consensus.”

The law grants the board broad discretion to define the scientific consensus and misinformation. Yet seven of the board’s 15 members, who are appointed by the Governor and state lawmakers, aren’t even physicians. The president is an environmental attorney. Another runs a life coaching company.

As an example of misinformation, a legislative analysis offers the hypothetical of a doctor advising patients to inject themselves with bleach to treat Covid. A doctor who did this could be sanctioned for “gross negligence” and sued for malpractice. But such egregious examples are rare and don’t need a new law to discipline.

The law’s real purpose is to silence doctors who disagree with the public-health establishment on controversial subjects on which there is substantial disagreement. One example is Covid vaccines for children, which most public-health officials recommend but the science is far from certain.

Florida Surgeon General Joseph Ladapo on Friday advised that young men not get mRNA vaccines after a state analysis found they experienced an 84% increase in cardiac-related deaths within 28 days of vaccination. He has also recommended against vaccinating healthy children because they are at low risk for severe illness, and the benefits don’t clearly exceed the uncertain risks.

Under California’s new law, a pediatrician who advises children against vaccination could have his license yanked. Ditto a gynecologist who tells a new mother that trace amounts of the mRNA vaccine have been found in breast milk. The latter is true, but the board might determine that it contradicts the consensus that vaccines are safe.

The expert consensus has often shifted during the pandemic. The law appears partly aimed at doctors who prescribe such drugs as ivermectin that haven’t been authorized by the Food and Drug Administration for Covid, but off-label prescribing is permitted under federal law.

A lawsuit filed last week by two doctors makes a strong argument that California’s law violates their First Amendment speech rights and is unconstitutionally vague under the Fourteenth Amendment. Even Mr. Newsom seemed to concede this by attaching a statement to his signature on the bill directing the board to punish only “those egregious instances in which a licensee is acting with malicious intent or clearly deviating from the required standard of care while interacting directly with a patient under their care.”

Yet the law isn’t narrowly tailored, and doctors have no way of knowing what will land them in the dock. It will chill discussions between patients and physicians. Doctors who want to be free to practice medicine can follow Dr. Ladapo to Florida.