When a PRD reads 9 at a checkpoint, what is the correct action?

• A. Probable cause
• B. Reasonable suspicion
• C. Stop and search
• D. Proceed without delay

Answer: (A)

A reading on a detector at a checkpoint is used to gauge how strong the justification is for taking investigative action. A PRD reading of nine is not just a vague hint; it meets the level of probable cause, meaning there is a reasonable basis to believe something unlawful or dangerous may be present based on objective measurement. That level of justification is what allows officers to escalate the response, such as stopping the vehicle and pursuing further investigation or search if warranted. Reasonable suspicion is a lower threshold and wouldn’t by itself justify the more intrusive steps, while proceeding without delay would ignore a significant signal. Stop and search is the action that follows from having probable cause, not the standard itself. So, the best interpretation is that probable cause exists in this situation, guiding the appropriate investigative response.