Say you take a family trip to Disney Land and your baby gets measles — perhaps suffers severe complications and can no longer hear or is left with brain damage. Would you want to sue the parents who voluntarily decided not to vaccinate their child, thus allowing the disease to pass to your baby?

It’s a growing debate, especially as measles cases in the United States have been rising steadily for the past few years, along with vaccine opt-outs. Should parents be held liable for unvaccinated children, if the decision was based only on a personal belief and they had no medical reason for opting out of their state’s immunization requirements?

“I am absolutely in favor of the idea of vaccination liability,” said Melinda Blanch, a New Haven, Connecticut mother of a 2-year-old son and 3-year-old daughter. “God forbid, I went out with my children and they were exposed to a deadly disease due to someone’s else irresponsibility, there would be some sort of price to pay.”

There’s evidence that, among certain geographic clusters, an increasing number of people are simply checking a box or signing a form that vaccination requirements are against the family’s personal beliefs — what’s known as nonmedical exemptions. Recent data showed California parents of kindergarteners are choosing not to vaccinate at over twice the rate than seven years ago. And a 2006 report in the Journal of the American Medical Association found higher rates of pertussis in states with liberal personal belief exemptions. In December, Grand Traverse County, Michigan experienced a whooping couch outbreak. The state, according to public health experts, made it so easy for parents to opt out of vaccinations that Michigan’s waiver rate was three times the national median.

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“In most states, it’s pretty easy to get a waiver and permission not to vaccinate,” said Arthur Caplan, head of the Division of Medical Ethics at New York University Langone Medical Center, who believes there’s too much “wiggle room” for parents to resist vaccinations. In response, Caplan has proposed holding non-vaccinators legally liable for the harm to individuals and communities, as a result of their non-vaccination decisions — when that harm can be proven. Alex Berezow, founding editor of Real Clear Science, recently went a step further and argued that parents who don’t vaccinate their children should go to jail.

“Imposing criminal liability on parents who don’t vaccinate would be tough,” Caplan explained, “because the state has given people the right to opt-out of vaccinating their children.”

Robyn Charron of Denver, Colorado, says her son had a bad reaction from a vaccination so she chose not to vaccinate her daughter. Picasa / Robyn Charron

Caplan believes a parent’s choice to opt out shouldn’t be “unrestricted or unfettered.” If an unvaccinated person visits a hospital nursery or a cancer ward, for example, or you send an unvaccinated child to daycare with newborns, Caplan believes parents should pay damages for death or disability resulting from a disease outbreak. “Liberty regarding vaccination ends at the start of a vulnerable person’s body,” Caplan said.

On the other side of the debate, Mary Holland, research scholar and director of the Graduate Lawyering Program at NYU Law School, points to the quagmire that parental liability presents. “Life has lots of risks,” Holland explained. “And the idea of imposing legal liability on parents who don’t vaccinate implies that vaccines are both perfectly safe and perfectly effective.”

“Vaccines aren’t perfect. Sometimes they don’t take,” said Holland. “There are vaccine strains of disease and wild strains, and allowing parents to sue one another gets you into some crazy places and complicated problems.” Take a parent who believes their first baby has had an adverse reaction to a vaccine.. If those parents decide against vaccinating a subsequent child, are they exercising a medical or a personal belief exemption — and would a person be able to sue them for their decision not to vaccinate?

Robyn Charron, a Denver, Colorado, parent, remembers experiencing seizures as a 5-year old, something she now believes was a reaction to routine vaccinations. When her son was born in 2009, she said that it never occurred to her not to vaccinate him. It was only after he fell into a “deep and disturbing sleep” and “woke repeatedly with a high pitched scream,” after his two-month-old vaccinations that she says she “made the connection.” A few months later, the little boy began suffering from a host of other medical issues, such as a severe peanut allergy and a series of related autoimmune disorders. As a result, she opted out of vaccinating her second child, a daughter. Is her decision a medical choice, or a personal one? It's a legal grey area. “I don’t think it’s fair to hold parents legally liable for this choice,” Charron said. “I made a careful decision based on my own experience and that of my first child. “

From a legal standpoint, vaccines in the U.S. are classified as “unavoidably unsafe,” meaning that injuries or deaths, however rare, may occur from the product. Holland points to the National Childhood Vaccine Injury Act of 1986, which gives doctors and manufactures liability protection for injuries caused by federally recommended vaccines. That means you can't sue your doctor or a vaccine-maker if your child has an adverse reaction. Those who oppose liability argue that it must cut both ways: if parents can sue one another for not vaccinating a child, then manufacturers should be subjected to the same tort system.

In his blog post, “8 reasons I haven’t vaccinated my daughter,” James Maskell, founder of Revive Primary Care, a holistic care website, cites his inability to fully use the legal system as the fourth cause for not vaccinating his child: “Unlike other drugs or products on the market, if my daughter has a serious, or even deadly, reaction to a vaccine, I cannot go all ‘Erin Brockovich’ and sue the doctor, the nurse, the drug company or form action lawsuit with others.”

If anti-vaccine trends continue, we’re likely only seeing the beginning of the liability debate. In fact, measles may be one of the easier legal test cases, as it’s one of the most contagious diseases. A person infected with the virus has a 90 percent chance of passing it on to someone else. But some parents, amid the outbreak, believe their children are still better off without the vaccine — and other families may start trying to hold them accountable for their decision.

Jacoba Urist is a health, education and culture journalist in New York City, who also writes for The Atlantic. Follow her on Twitter @JacobaUrist