Jim Pouillon was murdered in 2009 by a man who objected to the anti-abortion pamphlet he was distributing. Press coverage was scant, but some pro-choice groups, to their credit, denounced the murder. The New York Times didn't run articles suggesting that over-the-top pro-choice rhetoric - likening pro-lifers to the Taliban, accusing them of seeking to oppress women, urging a crackdown on their ability to protest abortion - had set the stage for the murder.

Pro-lifers refrained from suggesting that pro-choice groups bore responsibility for the murder. (I'm not aware of any exceptions to this generalization.) That was to their credit: The suggestion would have been obscene.

Pro-choicers have been less restrained in the wake of the recent murder of three people at a Planned Parenthood clinic in Colorado. They intend to turn the killings "into a political moment they say will put abortion opponents on the defensive." The Washington Post, which didn't cover Pouillon's murder, is reporting sympathetically on claims that the rhetoric of mainstream pro-lifers is to blame for the killings. Reporters are challenging pro-life politicians about the murders, which also didn't happen in the Pouillon case. The governor of Colorado says that "inflammatory rhetoric" from pro-lifers played a role.

Why might these cases have inspired such different reactions? It can't be that anti-abortion violence is a frequent occurrence, and thus fits into a larger story: It is only slightly more common than pro-abortion violence against adults, which is to say not very common at all.

I suspect the press is crediting the pro-choice spin on these killings because most journalists are themselves pro-choice and inclined to see pro-lifers as extremists. And so reporters who would consider it unfair to blame cop-killings on the rhetoric of some Black Lives Matter activists don't have the same sympathetic reflex when pro-lifers are in the dock.

Pro-lifers have decried the killings in Colorado, and complained that they're being smeared. But it has to be admitted that political rhetoric - all political activism, for that matter - can inspire violence. Many pro-lifers say that abortion is an evil on par with slavery. And some deranged people may try to play the part of John Brown in that analogy. Thankfully, such people are exceedingly rare.

When violence is committed in the name of a political movement, its responsible members have a duty to condemn it and to seek to root it out of their ranks - two things that pro- lifers have done. Do members of a movement have a duty to restrain their words for fear that madmen will commit outrages based on them? I think the answer is that political activists should refrain from saying anything more inflammatory than needed to make their case against the injustice that moves them - not so much from fear of the deranged as from love of their fellow citizens. The reason Hillary Clinton should stop saying that peaceful, run-of-the-mill pro-lifers are like terrorists is not that she's likely to inspire violence; it's that saying it makes our political debates even nastier and dumber than they already are.

Pro-life rhetoric isn't the real issue for pro-choicers anyway. The bedrock pro-life view - which, if you haven't figured it out already, I share - is that abortion is the unjust killing of living human beings. Any expression of that view, any political action taken to advance it, is going to offend many pro-choicers, and could lead some people to violent acts. Pro-choicers who want pro-lifers to stop saying that abortion kills unborn children aren't objecting to the pro-life movement's rhetoric; they're objecting to its existence.

And they're trying to score political points by associating the vast majority of pro-lifers with a tiny violent fringe. What should, but will not, give them pause is the example of the man who died trying to defend the victims in Colorado. Few people - pro-life, pro-choice or in between - are as courageous as Officer Garrett Swasey. But if you want an example of pro-life principles in action during this crime, look at him and not his killer.