After stopping a driver for a traffic violation, the police can investigate drivers for potential criminal activity as long as the investigation is justified by and related to the current circumstances. For example, if a driver exhibits uncontrolled behavior after being pulled over, an officer is reasonable in searching the car for alcohol or drugs. In contrast, police cannot use a traffic stop as a warrant for a full blown search of a driver's house.
When Is an Investigation Reasonable?
An officer must be able to point to specific and displayable facts, from which an average person could infer criminal activity. This standard of proof is much more lenient than the "preponderance of evidence" required in civil cases, and "probable cause" needed in other criminal searches. Even still, an officer has to show some minimal justification for the investigation. Without such justification, an officer can only detain a driver for as long as it takes to get their license and registration, ask a few routine questions, and issue the driver a ticket.
How Can a Lawyer Help Me?
If you have been unreasonably held by police officers during a routine traffic stop, you should contact a criminal attorney to help assert your rights. Because a police officer's right to investigate is based on personal opinion, it's hard to say with certainty whether an officer's search was unreasonable. However, an experienced attorney can look into cases similar to yours, and determine the likelihood of your particular case's success in court.