In an informative decision regarding the expansion of traffic stops by law enforcement, the Iowa Supreme Court held that when law enforcement, after making a valid traffic stop supported by reasonable suspicion, determines that the underlying reason for the stop is no longer present, must terminate the stop. For example, when a law enforcement officer stops a person because of expired registration, and determines that the registration is in fact current. Then that law enforcement officer cannot further question the driver if there is no reasonable suspicion of a crime.
At that point, the officer must simply allow the person to go on their way. However, it must be noted that this decision by the Iowa Supreme Court was determined on the basis of article I, section 8 of the Iowa Constitution, which provides more protection than the Fourth Amendment to the United States Constitution. “[C]abining official discretion to conduct searches is designed to prevent arbitrary use of police power. Limiting both the scope and duration of warrantless stops on the highway provides important means of fulfilling the constitutional purpose behind article I section 8, namely, ensuring that government power is exercised in a carefully limited manner.” State of Iowa v. Coleman (2017).