The New Scientist has an excellent story on student drug testing which reveals, among other things, that the stupid tests don't even work:

What's more, such tests can flag kids who are "clean" and miss genuine users. A study led by [director of the Adolescent Substance Abuse Program at Children's Hospital Boston, Sharon] Levy and published this month in Pediatrics (DOI: 01.1542/peds.2006-2278) examined recent drug tests of teenagers being treated for substance abuse. Of 710 drug tests performed, 85 gave incorrect results, either because the urine sample was too dilute to interpret properly, or because the test picked up prescription medicines.
…

"Drug tests can be very difficult to understand and interpret," says Levy. "There are lots of circumstances under which a kid could be using drugs and not test positive or have a positive test when they are not using drugs."

The tests were wrong 11.9% of the time. That's unbelievable. If 12 students out of 100 are getting bogus results, these tests aren't even close to being useful. And while follow-up tests can sometimes set things straight, consider this:

While the rules for federally funded testing say positive results must be checked by an approved lab, no such rules exist for the approximately 500 schools that are testing without federal grants. "Confirmatory testing adds a lot of cost. I don't think most schools are doing it." Levy says.

So the tests are wrong with frightening regularity, yet many schools don’t even have procedures for following up on positive results. That doesn't mean they aren't doing it, but it certainly raises doubts. Here's just one example of how a false positive test can destroy a student's relationship with their school.

As reformers, I believe we've been remiss in failing to emphasize false positives as a primary argument against student drug testing. It may prove difficult to establish the frequency with which they occur, but one is too many and the victims are highly sympathetic. When innocent non-users are accused and subjected to the stigma of drug use erroneously, all perceived values of the program are cast into doubt. This is an argument that might catch the attention of "clean" kids and proud parents who think they've got nothing to lose here.

Funny Side-note: SSDP's Tom Angell once urine tested himself for fun. Tom's reputation for partying is rather undistinguished, so we were certain he'd come up negative across the board. Instead, he came up positive for amphetamines and barbiturates (isn't that what killed Elvis?).

It was amusing that the test was so completely wrong the first time we ever tried it. But then we got chills thinking about families being torn apart by these fraudulent products. Come to think of it, there's nothing at all funny about any of this.