Things to consider when legalizing pot

While I am in agreement with legalizing marijuana, I believe there are a few ramifications we as a society would have to consider before just going out and legalizing it.  Some things to consider would be how to prevent/test for people driving under the influence and if there would be a legal limit, like .08 alcohol, to drive under.  There are plenty ways to test for marijuana, urine test, blood test, saliva test, etc., but each of these will show inaccurate readings if you are trying to decipher whether someone has just used it in the past hour or so.  For example, a saliva test, which would be the quickest way to test for a police officer on the side of the road, can show if the person has smoked marijuana in the past 12-24 hours.  There has to be a way that can be tested on the spot and with accuracy, similar to a breathalyzer, which would show whether the person was currently under the influence of marijuana.  Another thing to consider would be the possible increased amount of traffic accidents that could be related to marijuana use.  As we know not all drivers are as responsible as they should be and plenty drive while under the influence of alcohol, and ,while I know smoking pot does tend to make one a little lazier than normal, it is still obvious there will be plenty of people who will decide to drive while influenced.  This would lead to a great deal of scrutiny towards the new law of legalizing marijuana.  Once again, I want to confirm that I would be in 100% favor of legalizing marijuana, but I do believe the average supporter, as well as the opposer, should realize there are many hurdles we would have to face and figure out a solution to before we could legalize it.