Everyone reacts differently to marijuana, and theres so many different kinds out there too which only multiplies how mixed up the effects can be from one individual to the next...
I'm sure there's some scenarios where one guy taking a puff then passing it to his mate will not be impaired driving, whereas his mate doesn't have a hope in hell...
Just the same way that I'm sure there are some human beings out there with a crazy metabolism who can neck 4 pints of beer and still be perfectly sober after an hour.
Unfortunately you can only legislate on a general basis, which means you have to cater for the lowest common denominator. The general populace cannot be trusted with their own judgement, I think we can all agree on that at least.
So in short: No.