Attorneys are going to make a lot of money defending clients arrested for driving under the “influence” of marijuana. Most people know about the legal limits on the amount of alcohol in the blood. Traces of marijuana stay in the system a long time. Lawyers will argue that their client had traces of marijuana in their system because they smoked pot days earlier and the client was not high at the time of the arrest. I predict that the lawyers will clean out the clients bank accounts and blow smoke in court.
The legal limits for "intoxication" are arbitrary and set quite low for easier conviction.
By the way, blowing below 0.08 does not clear you, blowing above it makes it easier for them to convict you is all.
They can still pursue charges from 0.00-0.07. Have a beer and dare the officers to put you through whatever measures they want. And there is no breathalyzer requirement for a public intoxication charge (they can claim they saw you drink more than 2 adult beverages in an hour).
Those against "the war on drugs" are silent about the drugs of tobacco and alcohol.