So there are basically four ways to test for the presence of marijuana: saliva, blood, urine, and hair. Because smoked marijuana is only intoxicating for 4 - 6 hours, ideally we want to use a test that will only pop positive if someone has used the drug within the last 4 - 6 hours. Saliva testing roughly fits this profile. With blood you would still pop positive up to a day later, with urine up to a week or more later, and with hair testing up to several months later.
The good news though is that saliva testing is easy and cheap, and can be done in the field by police officers, unlike with blood testing. I think ultimately per se limits that are enforced with saliva testing (but not with the other methods) are reasonable, but the limits need to actually be based on science, not just pulled out of someone's ass.
(Of course this is assuming that better studies eventually do support per se limits for marijuana, which they don't seem to currently.)
Comments
"how would the level be tested?"
So there are basically four ways to test for the presence of marijuana: saliva, blood, urine, and hair. Because smoked marijuana is only intoxicating for 4 - 6 hours, ideally we want to use a test that will only pop positive if someone has used the drug within the last 4 - 6 hours. Saliva testing roughly fits this profile. With blood you would still pop positive up to a day later, with urine up to a week or more later, and with hair testing up to several months later.
The good news though is that saliva testing is easy and cheap, and can be done in the field by police officers, unlike with blood testing. I think ultimately per se limits that are enforced with saliva testing (but not with the other methods) are reasonable, but the limits need to actually be based on science, not just pulled out of someone's ass.
(Of course this is assuming that better studies eventually do support per se limits for marijuana, which they don't seem to currently.)