Police stop driver for lane control issues.  Police believe driver is impaired by narcotics and/or prescribed medications, but it is obvious that he suffers from serious leg injury and walks with limp.  Due to fact that child is in car, defendant is arrested and charged with Aggravated DWI following field sobriety tests.  Defense prepared to argue injury make driver incapable of performing most field sobriety tests and the tests are not designed to determine impairment by any particular class of narcotics or prescribed drugs.  DWI charge and Aggravated DWI charge dismissed prior to trial.