The great problem besetting the US Department of Homeland Security (DHS) is, of course, how on Earth to spend its mountains of federal pork on vaguely security-related stuff. One approach is to build gear which is only tangentially about security, but which might work - for example cryogenic superconductor power lines for New York. Another plan is to build something which is silly and unlikely to ever work, but which would be handy for security forces if it did - eg, handheld chunder rayguns.

Arguably the DHS tends to go for the latter type of effort more often than not. More evidence to back such an assessment appeared this week, as media reports began to circulate regarding the beautifully-named Project Hostile Intent.

This is not a sinister terrorist plan. It isn't even a double-sinister federal conspiracy to create terrorism where there was none before in order to establish a harsh police state, doubtless as prelude to government by alien invaders (excuse us while we get our tinfoil on).

No, Project Hostile Intent is supposedly all about detecting hostility rather than causing it - although, like many DHS measures, it has the potential for causing a good deal of ire among airline passengers.

DHS Impression of the mindreader tech in action.

The idea is that entrants to the USA would, basically, be mind-probed by amazing new tech to be developed by the Human Factors Division of the DHS Science & Technology directorate. The S&T boys swear blind that the technology will be "non-invasive" - oh, thank god - and will "identify deception and hostile intent in real time, on the spot... without ever impeding the flow of travellers".

This will be amazing stuff, if it works, though there could be a bit of a snag with false positives unless they can narrow it down. You'd need some way of detecting only hostility to the United States, rather than - say - hostility towards the DHS, which is common among otherwise righteous and patriotic Americans. As for "deception", you don't want the machinery to start pulling over all the adulterers, advertising copywriters, etc.

The DHS chaps themselves are relatively cagey about exactly how their mind-reader/lie-detector gear would work. The idea seems to be to employ a battery of technologies.

Cameras would snap pics or video of people's faces, which could then be automatically analysed for suspicious expressions - perhaps an anticipatory evil leer or vacant mindless drool at the prospect of finally attacking the hated Great Satan.

New Scientist reports that this is already done by specially-trained human screeners, but that's too manpower-intensive and time consuming for widespread use. Apart from expression scanning, the computers might check for suspicious eyeball movements - bad guys are well known to shiftily look left and right when worried.

There was no word on plans to seize and interrogate anyone whose eyes were too close together, or all bald men in wheelchairs stroking fluffy white cats.

Other notions might include laser or microwave scans which could measure how sweaty people's skin was, check for suspicious heartbeat patterns, or detect other signs of exaggerated fear as they entered the security channel - incontinence, perhaps.

If enough of these tests came up negative - suspicious face, heartbeat too fast, overly moist skin or pants - the luckless traveller would be drawn aside for a more thorough probing, though hopefully still "non-invasive".

It hasn't been hard to find sceptical securo-boffins to rubbish the DHS plans.

"There could be all kinds of reasons that might make people behave in certain ways that have nothing to do with terrorism," according to Anthony Richards, counter-terror egghead at St Andrews University, talking to the Guardian.

"If you have heightened security and there are a lot of police around, it could be possible that you can feel and look guilty even when you haven't done anything wrong," he added.

Or you might have done the wrong kind of wrongness. Apparently the pilot DHS human operated shiftiness-spotting programme, Screening Passengers through Observation Techniques (SPOT), has been subject to this problem.

"We have caught a number of individuals, from drug dealers to money launderers, and a double murderer in one case," the DHS' Chris White told New Scientist. But no terrorists.

Even so, Larry Willis, DHS boffinry chief of Project Hostile Intent, said:

"The early test results have us cautiously optimistic."

Peter McOwan of Queen Mary College in London, a top computer mood-recognition man, dismissed this brusquely.

"It's just like something from Minority Report," the testy boffin told New Scientist. "They have been watching too many Tom Cruise movies."

We see his point: though just to quibble a little, the Minority Report mind-probes were directed at bald mutant precogs in a swimming pool rather than airline passengers, and the enforcement personnel inflicted disabling vomit attacks on miscreants using club-style gizmos rather than dazzle-beam torches.

It's important to get these things right. ®