You can’t blame Karen Fletcher for deciding not to fight.

Had she lost, she faced the possibility of five years in prison. Under the plea agreement she accepted in early August, she got six months of house arrest, five years on probation and a $1,000 fine. But if the agreement allows Fletcher, of Donora, Pa., to avoid the more onerous punishment, it also allows us to avoid what surely would have been a violent collision between morality and the Constitution.

Karen Fletcher is a pornographer. And not just any old pornographer: the 56-year-old woman specializes in the rape, torture and murder of children. Indeed, children as young as infancy.

Here’s the twist: no children were hurt by – or even involved with – Fletcher’s pornography. She was prosecuted under federal obscenity statutes for writing “fiction” depicting the violent abuse of children. Fletcher has said the stories were her way of coping with sexual abuse she herself suffered as a child, a claim somewhat undercut by the fact that she was profiting from her work to the tune of 30 subscribers paying $10 a month to read the stories on her Web site.

All of which leaves me feeling … irresolute.

On the one hand, you have a woman doing a repellent thing with no discernible social value. By all available evidence, Fletcher’s imagination is a garbage barge ripening under the sun. The world of arts and letters – the world, period – is not diminished by the loss of her work.

On the other hand, you have a writer prosecuted – in America! – for something she wrote. That demands a ruminative pause if not, indeed, a full stop.

And here, I was going to draw a distinction between words and pictures, to say that Fletcher’s sin, awful as it was, involved “only” words, not graphic, stomach-churning images. But that would have been a hypocritical cop-out from someone who makes his living with “only” words and has spent years proselytizing for their power. So let us concede: Words have weight.

No, the question here is not whether Fletcher’s work is suitably repugnant, but whether the government has a role in regulating it or anything else whose production does not cause injury. If her stories did not harm any children, does the government have a compelling need to restrict them?

I don’t know that it does.

You may well disagree, and you’d have ample ground to do so. But you’d want to be careful that ground did not become the proverbial slippery slope. If offensiveness alone is reason enough for government to abridge the right of free expression, then what protects Stephen King, whose novel “Pet Sematary” includes the grisly desecration of a child’s grave? Or Vladimir Nabokov, whose novel “Lolita” depicts a middle-age man’s sexual obsession with an adolescent girl? Or, indeed, any writer whose work travels dark paths, sheds light on dank and shadowed corners of human existence?

What is the line where obscenity ends and art begins? And who gets to say?

Supreme Court Justice Potter Stewart once famously said of pornography that he could not define it with legal exactitude, “but I know it when I see it.” Many of us would doubtless agree with him.

But that standard, which works reasonably well among individuals, has potential to be a cudgel in the hands of government, particularly a government prone to extraordinary and even extralegal means of enforcing its vision of morality. So the prosecution of Karen Fletcher is a discomfiting thing.

I make no case for her as a great artist. My concern is for tomorrow’s great – or not so great – artist whose work deals in the repugnant and the disgusting. To be sanguine about his freedom and Fletcher’s fate requires that one trust government to understand and respect the difference.

And I, for one, do not.