Many years ago, when I was having my worldly possessions shipped from the US back to Australia, I was warned that if there was any pornography included then there was a risk of having it confiscated. Not because of anything illegal, of course, but because, well, that was one of the perks of being a customs officer.

Le plus ça  change … This morning, we find that “more than 20 Virgin Blue staff and managers from Sydney and Brisbane airports have been sacked for repeatedly using the airline’s computers to view and swap p-rnography”. Presumably they had downloaded it themselves rather than taken it from customers, but it is one more sign of the ubiquity of p-rn. (The airline’s name just adds to the humor potential.)

And this, of course, is the essential background to the continuing controversy over the new question on Customs forms that asks incoming travellers if they are carrying p-rn.

The problem is that the floodgates are already well and truly open.

People enjoy sex, and enjoy watching it. Millions carry porn on their laptops or USB devices every day, without thinking of it as in any way abnormal or controversial. Trying to control it is a hopeless task, as futile and as foolish as Steve Jobs’ efforts to keep the stuff off his latest new shiny thing.

But aha, say the fundamentalists, we’re not after porn in general, just things such as child pornography, mere possession of which is illegal in Australia and most other places. You’re asked to declare porn so that it can be screened for the illegal sort: Jim Wallace, of the Australian Christian Lobby, likened the new rule to “quarantine rules for wooden products for people entering the country”.

It’s not entirely clear what exotic diseases Wallace thinks people might catch from exposure to pornography, but for the sake of the argument let’s grant him the notion that some porn can be harmful. It should still be obvious that there are major differences between the porn inquisition and your quarantine check for foods and plant material:

(a) Determining whether wooden products carry a quarantine risk is a matter of expert judgement; there’s no way passengers can be expected to know, so there’s no obvious alternative to letting an official look at them. P-rn isn’t like that; any fool can tell whether what they’ve got is child p-rn or not. If the rules on that aren’t clear then they need to be changed, because anyone downloading it at home would be at risk, even if they never set foot in an airport.

(b) Wooden products are big, macro objects; they exist in real space in corners of your suitcase or wherever. But porn these days is mostly just patterns of electrons on laptops and the like. To search for it, a Customs officer is going to have to trawl through the electronic contents of your life, with all the obvious problems about privacy, confidentiality and potential for frame-ups. (Ben Sandilands surveyed some of these a couple of weeks ago.)

(c) Pornography is personal in a way that wooden products (by and large) are not. No one feels embarrassed at showing that native handicraft they picked up in Kenya to a complete stranger at the customs desk. But showing them the contents of one’s private sexual fantasies is rather a different matter. Most people will refuse, and the new rule will have no effect except to humiliate the conscientious and foster resentment and guilt among the rest.

These points are so obvious that it’s hard to imagine any sensible person could make the quarantine argument in good faith. Pretty clearly, the real agenda is to discredit and delegitimise porn in general. But that battle was lost some time ago.