There's a new blood sport on Britain's campuses. It's got everything: the thrill of the chase, the lust for blood and the satisfaction of the kill. Its high season is exam time, and its name is plagiarism.

At this very moment, all over the country, dedicated academic sleuths are in hot pursuit of equally determined student copyists and cheats.

It is a developing battle. New advances in online technologies have made it easier for students to cheat. They can download existing essays from the internet, commission someone to write one bespoke, or develop more personal strategies. One student simply borrowed his flatmate's computer and then copied, pasted and submitted the essays as his own. It was, of course, the hapless computer owner who was penalised for plagiarism.

But the pursuers can retaliate with their own state-of-the-art technology. Turnitin software is able to identify any text that appears on external webpages, as well as its own database. It can then produce a report that highlights the identical sections of text, the source and the percentage copied.

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It does have its limitations though. Electronic source- checkers are useful only for text-based work, so they're no help when you're dealing with artefacts. A fine example of concept burglary still wobbles proudly in our registry department - a plaster figure of the footballer Pele that was once handed in as ceramics coursework. Underneath, ineptly scratched out, three telltale words are still discernible: "Made in Taiwan".

Fashion is a trade with a long tradition of copying and some students start early. Last year, one third-year handed in a dress that was way beyond her usual level of skill. A member of the University of Westminster registry was dispatched to Oxford Street to match the garment and tracked it down in Warehouse. "She could at least have nicked something decent from Armani," was the pained reaction from the course leader.

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Fashion copiers can be pursued and caught. But how do the great plagiarist hunters even begin to track down their quarry in the jungles of art and design? Unmade beds, dead cows, flickering gallery lights and live runners are not copies: they are ironic statements, poststructuralist reflections adding layers of questioning to the very concept of the original.

The plagiarist is an even more elusive prey in music. George Harrison may have had to pay up a few years ago after a court recognised the striking similarity between My Sweet Lord and The Chiffons' hit He's So Fine. But that's a lot more straightforward than establishing who owns the copyright to a traditional folk song or to the hundreds of thousands of blues-based tunes all sharing the same 12-bar formation. And these days, with so many students indulging in DJ wizardry and the intricacies of scratching and sampling, artistic swiping and mixing of stolen phrases can hardly be categorised as plagiarism.

But the hunters do have their victories. Senior common rooms up and down the land echo with proud stories of success in nailing the sly, the stupid, the cunning and the most ingenious cheats. A colleague told me with great glee how he had discovered that one of our students had commissioned essays to be written on her behalf by posting assignment briefs online at RentACoder.com. Sadly for the student, she'd included links to her coursework briefs on our website, and was swiftly hunted down.

On another occasion, a student at a northern university included the name of a friend at Westminster among those who had helped him with his dissertation. It turned out that both students had submitted the same essay and were investigated by a joint committee from both institutions. There must have been some rubbing of hands by the academics who cracked that case.

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Indeed, Turnitin and other devices have become such seductive tools for detection that some academics have become quite obsessed with their power to track down even quite mild misdemeanours, in much the same way that Victorian schoolmasters would search out the slightest hints of masturbation among their boyhood charges.

As Michel Foucault elegantly explained in The History of Sexuality, it's all too easy for the game itself to become the point: "The pleasure that comes of exercising a power that questions, monitors, watches, spies, searches out, palpates, brings to light; and on the other hand, the pleasure that kindles at having to evade this power, flee from it, fool it, or travesty it." What results, he argues, is not a scaling down of the forbidden activity, but an escalation, dancing in "perpetual spirals of power and pleasure".

Turnitin encourages this kind of spiralling because it's impersonal. It allows you to spot the offence regardless of the identity of the student, so that the pursuit itself takes over: not so much Turnitin but Turn'emin.

There is, of course, only one way out of this game, one way to escape the spiral. Instead of starting with the act of detection, we should throw all our resources into ensuring that students don't contemplate plagiarism. That is why our academic integrity policy at Westminster recommends a change of emphasis from "offence" to "good practice" and from "catching" to "educating". Some are nervous that such an approach may seem to condone poor scholarship and dilute standards. But at least it may deter the overzealous from actually enjoying the chase.

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Of course, in the days when lecturers actually knew their students, they could recognise when a piece of work was out of character. But with swelling class sizes on so many courses, that kind of intimacy is becoming more difficult. That's why, all too often, personal understanding is being replaced by an inhuman slab of software.