Drug testing is very efficient way to exclude people from society. Think about a person who works regularly and smokes an occasional joint. Then there's a drug test and the person fails it. The results are that the person is sacked and she gets a stamp on her forehead. In some cases she is forced to go to a drug clinic or something as well / instead. She doesn't have any problem smoking a pot, say once in a month. The only problem is a drug test and authoritarian-conservative ideology beoynd it.

In Finland they have recently flashed possible obligatory drug tests for school children and there has been quite a lot of debate on drug tests on workplaces.
The leader of the Conservative party, Ville Itälä, is a great advocater of mandatory drug tests. He fails to understand (no wonder, he's a conservative..) that it's almost impossible even from purely financial side. The mandatory drug tests for school children once a year would cost much more than they spend money on rehabilitation programs.
Rarely I have to witness such an idiocy as mr Itälä said that even though drug tests are not reliable (true) it's better to have unreliable drug tests than no drug tests at all! So, hooray for control, discipline and capitalism -- no matter of few innocent getting into trouble.

There was also a work group investigating the legislation and possibilities of drug tests. In their report they rejected the idea of obligatory drug tests on workplaces. The report said that these tests should be voluntary and there shouldn't be any consuquences if a worker refuse to take a test. Of course it's very hard to prove if a possible discrimination was due to the refusal of drug test or not. The work group defended their conclusions saying that drug tests are the violation of personal privacy.

It doesn't surprise anyone that their report was attacked by conservative media by large. What they fail to understand that in these tests both unreliable and expensive they also do not detect the most of harder drugs. Cannabis can be detected from your urine after a month but such drugs as heroin and crack cannot be traced back after couple of days.

They say that drug tests are a vital condition for the operation of society. What if a schoolbus driver is on acid while working? Do you want to travel on a plane captained by a crackhead?
It's very scaring to notice that this kind of alarmism really affects on people. But just like you're able to recognize a drunken person I bet you can recognize if the captain of an aeroplane is tripping at the very moment.
Yes, there are problems doing drugs but do, please, not create them from nowhere. Once the problems are noticed why not to test them after? Thus we could advise the problemed to enrol a drug clinic or whatever...