At a DUI trial, the officer must prove he had “REASONABLE SUSPICION” to stop the driver.
Reasonable suspicion includes any traffic violation, unusual driving (slow speed, weaving within lane, sitting at a green light, etc.) suggesting a medical problem (seizure, heart attack, impairment, etc.)
Without reasonable suspicion to stop the driver, the judge should suppress all remaining evidences as unlawfully seized and the case should be dismissed.
A lawful police roadblock is one exception to the “reasonable suspicion” requirement.