Imagine:
Counterfeit passports are a rising problem. Terrorists have found ways to produce pretty convincing, fake passports and cross our borders at will. There is also an increasing 'phishing' operation, tricking unwitting people into buying from bogus sites that provide 'discount' passports.
The government decides to try and curtail the 'phishing' by providing ATM-style passport validation kiosks. After people buy passports, they can take them to these kiosks and get instant verification.
Good idea?
Maybe, until the terrorists start using the systems to validate and improve their fakes. Over time, the terrorists are overwhelmingly the biggests users of the validation kiosks. How handy, to have this simple way to test their new fakes! Ultimately, the terrorists become completely undetectable.
BYU's communications department has purchased a license to access turnitin.com, a system that allows people to submit their assignments and have them "checked" for plagiarism. The original intent was for teachers to be able to quickly check 'suspect' assignments. However, BYU has opened the system up to students as well.
Legitimate students -- first off, probably don't need this service at all. Fear-mongering might persuade them to use it, but all it will do is add another step to the already difficult process of writing a good paper.
For students who are interested in lightening their own loads through copying, however, this system is a great blessing. No longer are they forced to refrain from plagiarism out of fear of being caught -- they can use the same system the teachers will be, to modify copied text just as much as necessary until it is pronounced clean.
The technical process behind turnitin is a great idea. Providing stats on duplicate content, comparing against a wide body of known work -- fantastic. And allowing teachers to use that to help determine if a questionable paper has, indeed, lifted content verbatim from a little-known article published decades ago is a great step forward.
But opening that system to students serves no positive purpose, and assists the willing cheaters greatly. Indeed, it makes them virtually undetectable. It defeats its own goal.