A more thorough explanation:

Definition: A test conducted by law enforcement officers to determine if a driver is under the influence of drugs or alcohol while driving. It is also known as a field sobriety test.

Example: During a roadside test, a police officer may ask a driver to perform tasks such as walking in a straight line, standing on one leg, or following a moving object with their eyes. These tests are designed to assess a driver's balance, coordination, and ability to follow instructions.

Explanation: The example illustrates how a roadside test is used to determine if a driver is impaired while driving. The tasks given to the driver are meant to test their physical and cognitive abilities, which can be affected by drugs or alcohol. If a driver fails the roadside test, they may be arrested and charged with driving under the influence (DUI).