Amazon is easily the biggest behemoth in books right now. The company can make or break a book, easily enough. After all, it’s the largest book retailer–and retailer in general–in the world. A book listed on Amazon can be sold anywhere in the world, which is a pretty big deal.

In fact, more and more people do their book shopping on Amazon exclusively. That’s probably why Amazon started selling advertising.

You see, if you have a book on Amazon, you can advertise it through Amazon. That way, potential customers can learn about your book while looking at other books. It’s a pretty sweet deal.

That is, unless your book is about combatting gun violence, apparently.

No, really. Amazon recently blocked an ad regarding a book about ending gun violence. Why? Apparently, because it had a gun on the cover.

Earlier this year, I published a book called The End of Killing. It examines how new technology can help us end violence, with a focus on premeditated killing by firearms.

Shortly after it debuted, my publisher ran ads for the book on Amazon. A few weeks ago, we discovered that Amazon blocked the book’s ads after the mass shootings in Dayton and El Paso.

Why? Because the cover has a gun on it.

Further, they said they’d reinstate the ads only if we revised the cover. Here’s the note from Amazon’s legal team:

If approved with changes, the following changes must be made: This book cover is blocked at the moment due to the critical event policy that was activated 8/4/19 following the mass shootings in the U.S. We would be happy to revisit the ad after 8/12/19, but the cover image will not be approved as-is. An updated ad would need an image without a gun.

I was confused. The book’s thesis—indeed, my life’s work—is how we can end deaths by firearms. The book doesn’t promote guns. Far from it. In fact, my prime argument is that the lethality of firearms is a problem, but one that we can fix. And yet, Amazon wouldn’t allow us to promote those ideas in the aftermath of a deadly event that demonstrated the dire need for them.

Now, I’m not going to defend the author’s thesis or his life’s work. In fact, without reading the book itself, I’m going to bet he an I agree on nothing.

However, he goes on to suggest that places like Amazon, Google, and Facebook have yanked gun-related advertising not because they believe it will curb people buying guns, but to generate some positive PR. He presents it as his opinion, which he’s certainly entitled to, but I happen to think he’s right.

Of course, he’s upset because it impacts his book. I don’t know that he’d feel the same way if it was a book on tactical training or a buyers guide to firearms.

Not that it matters, either.

The truth is that Amazon is taking a vehemently anti-gun stance with their advertising program, one that readers and authors should both be well aware of.