Under the newly released White House National Drug Policy (link
http://www.whitehousedrugpolicy.gov/publications/policy/ndcs10/ndcs2010.pdf), Obama is calling for the presence of *any* marijuana in your body to be de jure evidence of driving under the influence.
A. Encourage States To Adopt Per Se Drug Impairment Laws
State laws regarding impaired driving are varied, but most State codes do not contain a separate offense for driving under the influence of drugs ... Fifteen states have passed laws clarifying that the presence of any illegal drug in a driver’s body is per se evidence of impaired driving ... expand the use of this standard to other states ...
Hat tip:
http://www.huffingtonpost.com/russ-belville/obama-drug-policy-calls-f_b_574483.html