In the state of Texas it is illegal to drive without a seat belt, Texas recently updated the Law giving an officer the right or the power to pull you over specifically because they saw you not wearing a seat belt or even in fact wearing a seat belt incorrectly that is underneath your army and not over your shoulder. Now what the cops are doing is standing at a red light specifically here on the south side of San Antonio at the corner of Military and Flores Street and they are walking between Stopped cars at a red light looking into your windows for the “express intent” of spotting violations specifically seat belts but others as well.
That is a violation of the Fourth Amendment, a cop can no more walk up to a window of your house and look in for the “express intent” of spotting violations than they can your car. The government will argue the “Plain Sight” rule, but that only applies if during the normal course of a legal search or while in police custody and ONLY if “unconcealed”.
{Plain sight rule is a principle of criminal law that permits a police officer to seize without warrant and use as evidence any item seen in plain view from a lawful position or during a legal search when the officer has probable cause to believe that the item is evidence of a crime.The “plain sight” rule recognizes that no citizen has a reasonable expectation of privacy with respect to unconcealed items within a vehicle in police custody.[State v. Gowans, 500 P.2d 641 (Ariz. Ct. App. 1972)])
If your driving passed a cop and they happen too see you not wearing a seat belt they can pull you over. They CAN NOT walk up to your car and peer in to YOUR window with the “express intent” to find violations. To do so constitutes a search and they need a WARRANT for that.