If you start a fire and harm your neighbor’s house, you may have to pay damages.

New laws in some states even ensure people who start forest fires are liable for the millions of dollars in damages. If you negligently start an outbreak of a preventable disease that harms your neighbor’s baby, you should be liable, too.

As measles spreads in New York, Washington state and elsewhere, states are considering how to ensure that more children are vaccinated against potentially deadly, preventable diseases. States can limit exemptions from school or day care vaccine requirements. States could also consider whether to allow tort suits — civil actions for damages — against non-vaccinating parents when their actions sicken others.

In 2018, measles cases and deaths increased globally, in large part due to vaccine hesitancy. In the United States, 2018 saw 372 cases of the disease across 26 states and the District of Columbia, and as of Feb. 28, we had seen 206 cases spread across 11 states so far in 2019. In response, several states, including New York and Washington, are considering tightening their school immunization laws by limiting or removing exemptions. California did that — and improved its children’s safety. Courts found its new law to be constitutional. But tight mandates do not help those already harmed by non-vaccinating.

Imagine a situation where parents did not vaccinate. Their unvaccinated child got (for example) measles. The child infected another, maybe a young baby, or a heart transplant recipient. Any number of things may happen to the victim. In the worst-case scenario, the victim dies (or gets subacute sclerosing panencephalitis (SSPE) — an always fatal complication — years later). In the best-case scenario, the family will have to take weeks off work.

Someone has to pays for these costs.

Why should that family pay, rather than the family whose choice to not vaccinate led to the harm? Suing for compensation could help.

The biggest barrier in this kind of suit is that, usually, there is no legal “duty to act.” If you sit sipping a drink, then see a baby crawl into a puddle, and go on sipping while the baby drowns, you will not be legally liable for not saving the baby, except in special circumstances. That is because requiring you to get involved in a situation you are not part of interferes with your autonomy much more than saying “if you got involved, take care.”

When we sue parents for not vaccinating, it appears to run into the “no duty to act” rule. But not necessarily.

First, there is a good argument that the decision not to vaccinate is much more of an active choice than usual bystander situations. Non-vaccinating parents are making a deliberate choice that often requires resisting social or medical pressure, or other actions. So the logic behind the distinction points the other way here.

Further, we do make exceptions and impose liability for nonaction when there are strong policy reasons. When parents decide not to vaccinate (absent a valid medical reason), they are choosing a bigger risk for their own child and rejecting expert opinion. That is bad enough; in a real sense, they are failing their own child. But they also put others at risk, others who did not choose that risk. Under these circumstances, there are good reasons to create an exception and find that parents who do not vaccinate violate a duty of care and should take personal responsibility when anyone is harmed.

This social choice can be made easier by legislative action. State legislatures can create laws that impose liability when non-vaccinating is shown to cause harm.

We compensate victims of intentional and unintentional harms in many contexts.

Victims of preventable diseases brought back by non-vaccinating deserve protection, too. Our tort system can help them, and legislatures can — and should — make it easier.

Dorit Reiss is a professor of law at UC Hastings College of the Law. Her research focuses on vaccines law and policy. She is also a vaccine advocate.