[locklock]

There's a difference between these tests (has this person smoked weed at any point in the last month, roughly?) and breathalyzer tests (is this person currently drunk?)

Showing up to work drunk vs. showing up to work two weeks after smoking weed are relatively different scenarios, to say the least.

[rjf72]

Hair tests for alcohol indicates average consumption over a period of months. It can also be detected using blood/urine tests over shorter periods of time, but similarly testing for usage rather than 'are you drunk right now' which hardly needs a test.