DUI tests, also known as field sobriety tests (or FST's), can be accurate in certain circumstances but are not always reliable indicators of impairment. FST's typically involve a series of physical and cognitive tests that police officers use to evaluate whether a driver is under the influence of alcohol or drugs. You can read more about FST's here.
Research has shown that the Standardized Field Sobriety tests, such as the horizontal gaze nystagmus (HGN) test, the walk-and-turn (WAT), and the one-leg stand (OLS), can accurately detect impairment in some cases. However, the accuracy of these tests can be affected by a variety of factors, including the individual's age, physical condition, and mental state, as well as external factors such as weather conditions and the type of surface on which the test is conducted.
Additionally, there are other factors that can affect the accuracy of DUI tests, including the training and experience of the officer conducting the test, and the personal health of the individual. For example, if the officer does not follow the proper procedures for administering the test or if the driver has a medical condition that affects their ability to perform the test, the results may not be accurate.
Overall, while DUI tests can be helpful in determining whether a driver is impaired, they should not be relied upon as the sole indicator of impairment. It is important to consider all of the available evidence, including the driver's behavior and other factors that may indicate impairment, before making a determination about whether to arrest someone for DUI.