I plead guilty to possession of marijuana in Michigan. I was given 1 yrs probation. I have smoke marijuana for over 15 yrs. After 6 months of not smoking, as a condition of my probation, I still haven't had a negative urine test. My probation officer is saying I have violated my probation (she says I'm smoking because my system should be clean in only 30 days. I'm not sure about that.) and is bring me up on charges of this violation plus the original charges. How can I prove I HAVE NOT SMOKED SINCE BEING CHARGED.

First off are you around people that do smoke pot?

If not and you have truly been off it for 6 months then ask for a hair folical test. It's a much longer track record and it will show your not a regular user.

THC is an interesting albeit perplexing molecule. It is unusual to be producing positive urine samples at 6 months, but with a 15 year history of use it is possible.

The hair test as mentioned above is probably your most economical route. Given your claim the test should be clear as it focuses on about 90 day period. The most recent.

Also, do you have the printout of the tests? The amount of THC/COOH might provide a starting point. The THC should be low and relatively stable. Test 1 should have been higher than test 3 and later tests should be consistently low. In addition, it may be possible to use a blood test to demonstrate a ratio between THC and the active metabolites. In all likelihood the test you are taking is looking only for THC-COOH in urine. But I'd first try the hair test. Courts are more impressed with it, and you can avoid arguing all the technicalities contained within the other methods.

Final note. There are a number of factors that can contribute to dislodging stored systemic THC. Weight loss, physical exertion (job, exercise, etc), and stress to mention the more prominent.