In general, it depends on the person, how much, how frequently and how long you've smoked. When I was in highschool, I needed to test clean for a job, (which they gave me 30 days notice? so they must not have cared that much) I tested weekly and on the 4th week I was clean. I was partaking a lot in HS, probably about an ounce a month (which is a ton for me, I'm sure more people smoke more)
They can take hair, and pretty much tell what you've done your entire life.
I find it amazing that with real child abuse and real reasons for CPS to be involved, a positive MJ test requires removal of the child. Wouldn't drug counseling and education be more helpful? AND allow the family to stay intact?
I'm in Ohio, which isn't "friendly", but we have a (huge) Meth problem, so maybe things are in a better perspective on what real drugs do to children, pregnant women and families. I was "dirty" most of my pregnancy, and no one said boo. I think I even admitted I smoked pot at my 1st prenatal. I thought there was a patient Dr. confidentiality. Or does MJ constitute child abuse that they have to report.