So when the Medical Board of California announced last week that it was moving to pull the Orange County pediatrician's medical license, it immediately set the stage for a new battle in the long-running fight over whether schoolchildren should be vaccinated.
At the heart of the case is whether Sears used sound medical practices when he wrote a doctor's note for a 2-year-old boy, saying he should have "no more routine childhood vaccines for the duration of his childhood." In its six-page accusation, the medical board said Sears made that conclusion without obtaining even basic medical information, such as a detailed history of vaccines the boy previously received and any reactions that occurred, before deciding to recommend against future immunizations.
Vaccination advocates see the medical board's action as essential to enforcing a new California law that prohibits parents from opting out of inoculations if they want to send their children to school unless they have a doctor's note.
As the law took effect this year for children entering day care, kindergarten and seventh grade, websites popped up coaching parents how to request a medical exemption, including lists of doctors believed to be open to writing these notes.
For UC Hastings law professor Dorit Reiss, the meaning behind Sears' case is clear: "We're not just going to stand by and let you give unjustified exemptions and prevent children from being protected from these diseases."
But vaccination skeptics both in California and nationally expressed alarm at the action against Sears, fearing it marks the beginning of a witch hunt against doctors and others who object to the state vaccination schedule.
"They're using Dr. Sears as an example — a shot across all the doctors' bows," said Rebecca Estepp, who is part of an advocacy group that opposed the new vaccine law.
One group, called Oregonians for Medical Freedom, called on the medical board to drop the case against Sears and "respect the sanctity of the doctor-patient relationship," and declared Monday "Stand With Sears Day."
Dr. Jay Gordon, a Santa Monica pediatrician who also opposes stricter vaccine laws, called the medical board's action an attack on a physician's ability to judge whether a patient should be exempt from a vaccine.
Gordon said he has known Sears for years and called him "seriously dedicated to the health and welfare of children." Gordon said that although the state found fault with Sears for notes it considered incomplete, many doctors use similar shorthand.
"I know that somebody could challenge my medical exemptions, but I'm complying with the letter of the law and the spirit of the law and I'm very bothered by this," Gordon said. "For all I know, I'm the next person they're planning to pursue."
Sears, author of "The Vaccine Book: Making the Right Decision for Your Child," a bestseller that offers advice to parents who object to immunizations, declined to comment.
The new law strengthening vaccine requirements was inspired by an outbreak of measles that began in December 2014 at Disneyland and left more than 100 children and adults sick in California, seven other states and two other countries. It was the worst measles outbreak in California since 1991, fueled by the number of parents who declined to vaccinate their children, experts concluded.
Measles also broke out in Orange County in spring 2014, infecting 22 people. In 2008, a 7-year-old unimmunized boy triggered a measles outbreak in San Diego after he returned, infected, from a family trip to Switzerland, spreading the disease to children at school and a doctor's office.
State data show that measles vaccination levels among kindergartners in recent years have been dropping low enough to permit widespread measles outbreaks. The Times found that many schools with high levels of vaccine exemptions were in wealthier areas, such as south Orange County and the Westside of Los Angeles.
The state law passed in 2015 was an effort to end the option that allowed parents to cite personal beliefs as a reason to avoid state-required vaccines for children attending school.
Sears has been a vocal opponent of the stronger vaccine law, raising worries about the safety of vaccines. Public health experts say fears about vaccine safety are rooted in a report linking vaccines to autism that has since been discredited as a fraud, based on fabricated data. Officials say the nation's childhood immunization schedule is safe and vital to public health.
Dr. Richard Pan, a pediatrician and state senator who sponsored the law, said the Sears case is about alleged negligence — not that Sears gave the exemption.
"In the end, you need to show that you've demonstrated due care," Pan said, "that you're acting based on the best interests of the patient."
If a doctor believed that his patient really was harmed by a vaccine and suffered problems such as kidney failure or inflammation of the brain, as written in Sears' note, there should be supporting documentation showing proper care and follow-up to a specialist, said L.J Tan, an official with the Immunization Action Coalition who has previously advised the federal government on vaccine policy.
"You want to make sure that when you hand the patient off to a neurologist, all the details are in the patient's medical record," Tan said.
Cassandra Hockenson, a spokeswoman for the medical board, declined to elaborate on the case involving Sears but said the agency began investigating after receiving a complaint. "The Medical Board of California's mission is consumer protection and to ensure that the proper standard of care is exercised," she said.
Experts say there are many legitimate reasons for a patient to be exempted from a vaccine: an allergy to gelatin or latex, for example. But legitimate medical exemptions to vaccines are backed up with evidence, they said.
Two of the nation's leading pediatric infectious disease specialists say they cannot think of any reason why a 2-year-old boy should receive a sweeping recommendation against all future vaccines for the duration of his childhood.
"This doesn't make any sense," said Dr. James Cherry, a UCLA research professor and primary editor of the Textbook of Pediatric Infectious Diseases. Even children with cancer can safely get certain vaccines, he said.
"The vaccines are all made differently. They're all based on different biological principles," said Dr. Paul Offit, infectious diseases expert at Children's Hospital of Philadelphia. "I can't understand how a physician could conclude that a person shouldn't get any vaccines" for the rest of childhood.
A more logical step is testing to see what, if any, vaccine is causing a bad reaction, Offit said, and then figure out what other vaccines could be safely given to the child.
Sears now faces a settlement conference, where the physician can agree to disciplinary action in negotiations with the medical board. If an agreement is not reached, Sears would then face a hearing before an administrative law judge, who would recommend a decision, such as revoking or suspending Sears' medical license, or suggest a lesser punishment, including probation or a reprimand. The judge could also propose dismissing the case.
The judge's recommendation will then be sent to the 15-member medical board, whose members are appointed by Gov. Jerry Brown and legislative leaders. The board makes the final call.
Times librarian Scott Wilson contributed to this report.