Answer: Those field sobriety tests can be various. The standardized field sobriety tests are the NHTSA—the National Highway Traffic Safety Administration— tests that have been validated by NHTSA. They’ve done some lab and field work to show that they are valid indications of impairment, under certain circumstances. Because those are the standardized tests, they must be done the same way each and every time or they may not be valid. But those specific tests that have been validated under some circumstances at least are: the horizontal gaze nystagmus, which is the eye test; the walk-and-turn test; and the one-leg stand test.