Is there a blood test to test for marijuana? if so how far back does it detect?

Question

Is there a blood test to test for marijuana? if so how far back does it detect?

Answer 1

the test tests for THC (which is in weed) and it canleave tracesin your blood stream for up to a month

Answer 2

i just asked, and the Dr told me that it takes 2 weeks before the test won't pick it up.

depending on how much was in your system, i presume.  

Answer 3

Yes, there is. It's the most definitive because it tests for the actual THC, not the metabolites produced by the body after consuming THC. The test will come back clean if the donor hasn't smoked for 6 days or more.