Phases of DUI Detection
The first phase is when the officer has a suspicion that a DUI offense is occuring.In phase one the officer must decide whether there is probable cause to stop or approach the vehicle. If an officer stops a vehicle without probable cause, everything that occurs after the stop is inadmissible as evidence because it was obtained in violation of the Fourth Amendment of the United States Constitution. The unlawful stop is referred to as the "poisonous tree". The evidence obtained as a result of the unlawful stop is considered a "fruit" of that "poisonous tree" (Famous U.S. Supreme Court case, WONG SUN).
The second phase is considered to be when the officer makes contact with the driver.officer makes contact with the driver...
The third phase occurs when the officer screens (or tests) a driver prior to making an arrest decision.officer screens (or tests) a driver prior to making an arrest decision...