Notwithstanding any other provision of law and for purposes of prosecutions under Section 32-5A-191, a law enforcement witness may give testimony solely on the issue of impairment, and not on the issue of specific alcohol or drug concentration levels, based on the results of a horizontal gaze nystagmus test when the test is administered in accordance with the individual’s training and administered by an individual who has successfully completed training in the horizontal gaze nystagmus test.