This is a very interesting recent documentary about how faulty drug testing methodology resulted in children being taken from parents in Canada. As far as I can remember from the documentary this testing was also used in the US but is no longer now, once the errors were discovered. It is just under 40 minutes long As it is a short documentary it doesn't go into a lot of detail, but it sounded like this test was taken as gospel without it being checked/verified by an outside agency. It sounded like the victims and lawyers (and possibly their medical advisors) came up with the solution when they realised the test was giving false positives. It showed the problem of an over-reliance on tests which have negative consequences for those who get them, even though other evidence points in other directions. It was like it didn't occur to the authorities to question the lab methodology, even when there was evidence against its findings. Very worrying.