So here’s what I wonder about the Justice Department’s planned new obscenity crackdown. As we know, there’s lots of porn of all varieties out there on the Internet. I don’t know how much of it is produced in the U.S. — but even if it’s 75 percent, and every single U.S. producer is shut down, wouldn’t foreign sites happily take up the slack?

It’s not like Americans have some great irreproducible national skills in smut-making, or like it takes a $100 million Hollywood budget to make a porn movie. Foreign porn will doubtless be quite an adequate substitute for the U.S. market. Plus the foreign distributors might even be able to make and distribute copies of the existing U.S.-produced stock — I doubt that the imprisoned copyright owners will be suing them for infringement (unless the U.S. government seizes the copyrights, becomes the world #1 pornography owner, starts trying to enforce the copyrights against overseas distributors, and gets foreign courts to honor those copyrights, which is far from certain and likely far from cheap).

And even if overall world production of porn somehow improbably falls by 75 percent, will that seriously affect the typical porn consumer’s diet? Does it matter whether you have, say, 100,000 porn titles (and live feeds) to choose from, or just 25,000? So we have three possible outcomes:

(1) The U.S. spends who knows how many prosecutorial and technical resources going after U.S. pornographers. A bunch of them get imprisoned. U.S. consumers keep using the same amount of porn as before. Maybe they can’t get porn on cable channels or in hotel rooms any more, but they can get more than they ever wanted on the Internet. Nor do I think that the crackdown will somehow subtly affect consumers’ attitudes about the morality of porn — it seems highly unlikely that potential porn consumers will decide to stop getting it because they hear that some porn producers are being prosecuted.

The only potential benefit: If you really think that the porn industry is very bad for its actors, you’re at least sparing Americans that harm, and shifting it off-shore instead. Other than that: The investment of major prosecutorial resources yields a net practical benefit of roughly zero.

(2) The government gets understandably outraged by the “foreign smut loophole.” “Given all the millions that we’ve invested in going after the domestic porn industry, how can we tolerate all our work being undone by foreign filth-peddlers?,” pornography prosecutors and their political allies would ask. So they unveil the solution, in fact pretty much the only solution that will work: Nationwide filtering.

It’s true: Going after cyberporn isn’t really that tough — if you require every service provider in the nation to block access to all sites that are on a constantly updated government-run “Forbidden Off-Shore Site” list. Of course, there couldn’t be any trials applying community standards and the like before a site is added to the list; that would take far too long. The government would have to be able to just order a site instantly blocked, without any hearing with an opportunity for the other side to respond, since even a quick response would take up too much time, and would let the porn sites just move from location to location every several weeks.

Sure, that sounds like a violation of First Amendment procedural rules, even when the government is going after substantively unprotected obscenity. Sure, that would make it easier for the government to put all sorts of other sites on the list. Sure, it’s a substantially more intrusive step than any of the Internet regulations we’ve seen so far, and is substantially more intrusive in some ways than virtually any speech restriction in American history. (I say in some ways, not in all ways, since it would have a limited substantive focus — but the procedure would be unprecedently restrictive, and First Amendment law has always recognized the practical importance of procedure.) But it’s the only approach that has any hope of really reducing the accessibility of porn to American consumers.

(3) Finally, the government can go after the users: Set up “honeypot” sites (seriously, that would be the technically correct name for them) that would look like normal offshore pornography sites. Draw people in to buy the stuff. Figure out who the buyers are (you’d have to ban any anonymizer Web sites that might be used to hide such transactions, by setting up some sort of mandatory filtering such as what I described in option (2). Then arrest them and prosecute them. Heck, lock each one up for several years like you would a child porn buyer. Make him register as a sex offender. Seize his house on the theory that it’s a forfeitable asset, since it was used to facilitate an illegal transaction. All because he, or he and his wife, like to get turned on by watching pictures of people having sex. Then repeat for however many people it takes to get everyone scared of the Smut Police.

So we really have three possible outcomes:

(1) The crackdown on porn is doomed to be utterly ineffective at preventing the supposedly harmful effects of porn on its viewers, and on the viewers’ neighbors.

(2) The crackdown on porn will be made effective — by implementing a comprehensive government-mandated filtering system run by some administrative agency that constantly monitors the Net and requires private service providers to block any sites that the agency says are obscene.

(3) The crackdown on porn will turn into a full-fledged War on Smut that will be made effective by prosecuting, imprisoning, and seizing the assets of porn buyers.

Seriously, I don’t see many other alternatives. The government could try to put pressure on financial intermediaries, for instance requiring Visa and MasterCard to refuse transactions with certain locations; but unless that’s made just as intrusive as option #2 above, it will be hopelessly ineffective, since sites can easily just periodically change their payee names, or use various offshore intermediaries. The government might also try to persuade foreign countries to join its campaign, but I’m pretty sure that won’t work, either. First, the Europeans are apparently fairly tolerant of much porn; and, second, I highly doubt that we can persuade every poor third-world country, some of which have thriving trades in real flesh, to spend its resources creating and actually enforcing anti-porn laws, in the face of whatever payoffs the porn industry is willing to provide.

So, supporters of the Justice Department’s plans, which do you prefer — #1, #2, or #3? Note that I’m not asking whether porn is bad, or whether porn should be constitutionally protected. I’m certainly not asking whether we’d be better off in some hypothetical porn-free world (just like no sensible debate about alcohol, drug, or gun policy should ask whether we’d be better off in some hypothetical alcohol‑, drug‑, or gun-free world).

I’m asking: How can the government’s policy possibly achieve its stated goals, without creating an unprecedentedly intrusive censorship machinery, one that’s far, far beyond what the Justice Department is talking about right now?