It is a shibbloeth conjured by your fevered paranoia.
When you give the government the power to determine what is and isn't pornography, you're taking the short end of a very long bet.
If you love the war on drugs--no-knock raids, property seizure on mere accusation of wrongdoing, et cetera--then you're gonna LOVE the war on porn. One .jpeg file of a nekkid woman--quite possibly put on your computer without your knowledge while you were on the Internet--and the cops can seize everything you own. Great idea.