Reiss points to the children in Germany who contracted SSPE, and the medical costs, lost work hours, and expenses the families incurred. “Nothing can fully compensate these families for the suffering they went through,” she acknowledges. “However, monetary compensation can help the families rebuild their lives and prevent additional suffering from the financial, on top of the human, losses they suffered.” People who fail to vaccinate their children create real, sometimes catastrophic costs when they infect others. As a matter of justice, Reiss argues, those costs should be born by those who negligently decided, against all the scientific evidence, to expose others to risk.

Lawsuits have not been widely employed so far; Reiss told me that, to her knowledge, no one has actually sued someone for infecting their child due to failure to vaccinate. But lawsuits do have some advantages.

Perhaps the biggest one is that they would be relatively simple to implement. Specific legislation authorizing lawsuits in these cases would make them easier to win, but such legislation isn’t necessary, Reiss argues. It’s true that many states offer exemptions for parents who don’t want to vaccinate their kids, but such exemptions don’t necessarily rule out lawsuits. State legislatures didn’t consider the issue of lawsuits when they created the exemptions, and “depriving a family who was harmed by another’s negligence is a big deal, and deciding the legislature did it inadvertently is a big leap,” Reiss told me. She added, “Actions can be legal but not reasonable. It’s legal to have a stack of hay in your yard, but if it’s a fire hazard and you start a fire, you may be liable … The fact that behavior is legal does not mean you’re not negligent to engage in it—and if you’re negligent and someone is hurt, in our system you usually have to pay.”