The impairment test is very subjective. I have failed it a few times and in fact now I tell the cop 'don't waste your time with the impairment test just give me the breath test'. Each time I was .03 or .04 and the cop said 'have a nice day'.

Failing the impairment test is NOT breaking the law. NOT. It is only a test to see if OTHER TESTS should be done or not. So AGAIN, what OTHER TEST would be given for pot? A blood test will show pot in the blood but for over 30 days or more. There isn't a test to show that someone is too stoned at a specific time and place like there is with booze. Also as I said there isn't a standard for impairment (e.g. a .08 standard like with booze).

Do you see the major differences now?