Another point to remember is that, if the US banned porn, such a ban would be imposible to enforce without massive government intrusiveness. With the internet, porn could be easily transmitted from anywhere in the world. Unlike liquor, there is no physical way to interdict porn. Government would be faced with either a totally meaningless ban, or be required to monitor everyone's internet usage.
Of course, I also think you would have a very hard time finding juries willing to convict people for violating such a law. I know I would certainly refuse to convict someone for looking at dirty movies.
Another point to remember is that, if the US banned porn, such a ban would be imposible to enforce without massive government intrusiveness. That's what we were trying to get across earlier, that it would require tyranny. BTW, you'd never get on that jury due to voir dire, and you'd probably get thrown off if you tried to keep to your principles.