A measles outbreak in Washington state has led Gov. Jay Inslee to declare a state of emergency. Meanwhile, health officials in Georgia, Hawaii, Oregon, and New York have also confirmed cases of measles in their states. This follows major outbreaks in several states over the last few years. There are a growing number of cases of the highly contagious disease that just 18 years ago was declared by the Centers for Disease Control to have been eradicated from the U.S. So what has led to these new cases?

In Washington, the cause is clear: non-vaccinated individuals. This fact has shown a bright spotlight on an increasingly heated debate over the broader societal health risks posed by the growing anti-vaccination trend.

As we’ve said before, those who opt out of vaccines benefit from what’s known as herd immunity. In other words, as long as about 90% of people are vaccinated, the “more enlightened” few may choose to avoid doing so and suffer little consequence. But there is a mathematical limit to this gamble, and it’s often upper-class liberals who are rolling the dice. In the affected areas of Washington, vaccination rates are only about 75%.

Anti-vaxxers blame vaccinations for the supposed rise in rates of certain autoimmune disorders, but this belief is born out of a rejection or misunderstanding of mainstream medical practice due in part to debunked pseudo-scientific explanations. This skepticism is coupled with a strong antipathy toward corporations or a deep distrust of governmental authority, and there’s a growing belief among some Americans that vaccinations are more of a health problem than a solution.

While a majority of Americans may disagree with anti-vaxxers and see their views as dangerously foolish, the First Amendment protects their right to hold and express them. However, the real rub comes when one’s individual beliefs may have direct impact upon the physical health and well-being of society at large. The current outbreak of measles demonstrates this balance and raises the question: When does protecting public health supersede the freedom of the individual to live according to how they see fit? Or to put it another way, when does the government have the right or responsibility to compel individuals to conform to certain behavioral expectations irrespective of personally held beliefs? As 19th-century physician Oliver Wendell Holmes put it, “The right to swing my fist ends where the other man’s nose begins.” The choice to refuse vaccination — when rooted in vain conceit rather than medical reality — endangers others.

Frankly, given the devastating history of diseases like the measles and polio and the amazing medical breakthroughs that have (or had) virtually eradicated many of these diseases, profoundly improving the lives and health of all Americans living today, it is mind-boggling that this is even an issue up for debate.