“They’re very blatant,” said Dorit Reiss, a professor at UC Law San Francisco who studies vaccine law and policy.

The group’s founder and director is William Lionberger, a chiropractor who has been licensed to practice in California since 1981, and who once maintained a practice north of San Diego. According to public records, he has also served as a police officer in a town near Sedona. (Lionberger declined a request for an on-the-record interview, and the organization did not answer a list of questions from Undark.) Interviewers who have hosted Lionberger on their shows describe him as affiliated with America’s Frontline Doctors, a group that opposed Covid-19 vaccines and other public health measures while promoting unproven treatments like hydroxychloroquine.

Frontline Health Advocates’ webpage was first registered in March 2022, with a name echoing that of America’s Frontline Doctors. By April of that year, the website was inviting visitors to “Get your exemption now.” In a 2023 interview, Lionberger described having a “team of medical experts” who “work with all kinds of situations,” evaluating clients both for “regular vax injuries and regular vax exemptive conditions.”

He added: “People now don’t even want their kids to get anywhere near a regular vaccine.”

The group employs a pair of distinctive legal strategies. One of these is to form itself as something called a Private Ministerial Association. Online, some groups that help set up such private associations describe them as offering special First Amendment protections. A membership application document hosted on Frontline’s website describes the group as “a private, unincorporated ministry that operates as much as possible, outside the jurisdiction of government entities, agencies, officers, agents, contractors, and other representatives, as protected by law.”

Another strategy is to invoke federal disability law. In the 2023 interview, Lionberger boasted that they drew on “the most powerful thing that you can bring against discrimination”—specifically, federal protections. A promotional video posted on the Frontline website makes a similar claim, advertising waivers “supported by the protections under US federal laws.” Undark obtained three near-identical exemptions sent to New York families in 2024. In them, Frontline argues that the client’s need for a medical exemption is protected under the Americans with Disabilities Act, or ADA, which guarantees certain accommodations for people with disabilities and other medical needs.