The following was published in the Biddeford-Saco?Journal Tribune Sunday edition, 2/8/2015.

In America, enshrined in our First Amendment, we have a right to voicing our own opinions. But ever since the Charlie Hebdo attacks in France, Ive been thinking about whether free speech does have limits. If what I say ends up hurting others, or even myself, I may have a right to say it& but should I?

We call ourselves the freest country in the world, but the vast majority of Americans accept laws that put limits on behavior. Though my cars speedometer goes up to 160 miles per hour, I rarely exceed half that on the Maine Turnpike on my way to work at the Wells Reserve. Even though Im free to go faster than the speed limit, I dont, partly because tickets are expensive, but mostly because doing 120 would endanger my life and others. Excessive speeding is against the law; its also against common sense.

In this supposedly free country, I cant legally build a 300-foot-tall wooden structure on my little patch of suburbia. Zoning and building codes limit my freedom of carpentry expression. This is a good thing. I imagine that I could test some free speech limits by erecting a 300-foot-tall wooden cross, but it would still likely fall on my neighbors and kill them (or act as a superb lightning rod, divine or otherwise).

Common sense, shared space, public safety, societal responsibility: these all put boundaries on free expression. While we are free to test those boundaries, there are consequences.

Take, for instance, the recent measles outbreak in the news this week. The Centers for Disease Control and Prevention declared measles eradicated in 2000, after only a few dozen containable cases were regularly appearing in the U.S. annually. Thanks to widespread MMR (measles-mumps-rubella) vaccination campaigns in the mid-1990s, our countrys herd immunity had reached a critical 93-94% coverage rate. Outbreaks could thenceforth be contained if we, heeding the advice of scientists and doctors, kept on vaccinating our children.

But a virulent anti-vaccine campaign arose in the late 90s and got a boost from surging autism diagnosis rates. Based on a fraudulent, discredited research paper, along with hundreds of anecdotes-but-not-data, the anti-vaxxers succeeded in sowing doubt in enough parents minds that vaccination rates in some communities declined. The majority of the nations unvaccinated children have parents who seek exemptions from the shots on philosophical grounds. According to the CDC, the national median for vaccination rates across the 50 states in 2013-14 was 94.7% for kindergartners, down from its peak. (In Maine in 2013-14, our rate was 89.9% and exemptions are rising.) Parents rights to their own opinions are fueling a measles comeback: nationally, in 2014, the number of measles cases hit a 20-year high. As of last week, 14 states are reporting measles cases.

So while celebrities like Jenny McCarthy and presidential hopefuls like Chris Christie can declaim that its a parents choice to vaccinate their children, expressing that freedom holds real risks. What if these non-scientist famous people are wrong about vaccines, and someone dies? That is quite possible, given enough resurgence: before measles vaccination began in 1963, millions of Americans annually contracted the disease, thousands suffered complications like encephalitis, and 400-500 died.

After this past falls outbreak of Ebola hysteria, youd think our collective response to infectious disease would be a little sharper. Nine times as contagious as Ebola, measles is not that serious for most people, but it can still kill infants and the immune-compromised. We owe those defenseless patients our protection. Fortunately, a very effective vaccine exists. But it has to be deployed widely to work.

We have to trust science as much as scientists and doctors do. Last week, the Pew Research Center released a report on a survey of the general public and scientists that found that only 68% of the public believes childhood vaccines such as MMR should be required, compared to 86% of scientists. What else might we be misguided about? The same survey also discovered that:

• 50% of the public believes that climate change is mostly due to human activity, compared to 87% of scientists;
• 65% of the public believes humans and other living things have evolved over time, compared to 98% of scientists.

If you read this column regularly, you know the faith I place in science and evidence. But while I trust data, I admit that it doesnt always make for the strongest appeal to the better angels of our nature. Ive heard enough times from friends and relatives that our freedoms cant be curtailed just because some egghead in a lab coat says they should.

So, one last story of freedom and limits. My son, a second grader, has a Valentines Day party coming up in his class. When I was in grade school, we had the freedom to make and give out valentines to our friends and our crushes. We could also neglect our enemies or the icky kids. We were not told, as the kids today seemingly are, that if youre bringing in Valentines cards, you must bring one for every classmate. As little as thirty years ago, innocent students could be infected with the shame and guilt of NOT receiving any heart-shaped cards on Valentines Day. Think of it what you will  nanny-state coddling or an important life lesson  but nowadays, teachers inoculate against the Valentine misery that children used to unwittingly inflict on one another.

Now everyone gets a Valentine, and no one gets heartbroken. If everyone got their measles shots, almost no one would get the measles. Wouldnt that be better?

Nik Charov is president of Laudholm Trust, the nonprofit partner of the Wells National Estuarine Research Reserve in Wells, Maine. His Sunday column, Between Two Worlds, ventures forth from the intersection of art and science, past and future, faith and data. More at wellsreserve.org/twoworlds.