What is the definition of DUI in Georgia? Does it only apply to alcohol or can you also be DUI for smoking marijuana?

Answer:  This question could require a long answer, but to summarize:  It is illegal to drive a vehicle in a less safe manner due to the alcohol you have consumed.  It is illegal to drive a vehicle with an alcohol level above .02 if you are a minor, .04 if you are a truck driver (have a CDL license), and over .08 if you are over 21.  It is illegal to drive in a less safe manner while under the influence of drugs, illegal drugs or prescription drugs and the state is required to show that the drugs consumed caused you to be a less safe driver due to the consumption of those drugs.