If you are arrested for possession of marijuana and it is less than one ounce, you are charged by prosecutors with a misdemeanor. If it is greater than an ounce, or there are allegations of dealing or distribution, then it will be a felony violation of the Georgia Controlled Substance Act (VGCSA). You can also be charged with possession of drug related objects (like pipes).
In addition, you can be charged with driving under the influence of marijuana, or DUI - drugs. Even though marijuana is not closely akin to impaired driving the way that alcohol intoxication is, if the officer pulls you over for a traffic violation, and then thinks he smells some marijuana, there is a good chance he will arrest he for some type of marijuana offense.
While a breathalyzer or intoxilizer test is used for most DUI - alcohol offenses, a blood test is generally ordered by the officer if you are arrested for DUI - marijuana or some other drug. This test often takes months to come back from the Georgia law enforcement crime lab, but when it does, even if there are trace amounts (and even though there is no indication of on what date and time that marijuana was consumed) the prosecuting attorney will use that as evidence against you.