IF THERE IS A REASONABLE BASIS FOR A TRAFFIC STOP, THAT IS ALL THAT IS REQUIRED
An objectively reasonable belief is all the police need to stop your car. No violation of the law is required.
"Reasonable" but not necessarily "correct" is the standardIf you believed that the police cannot pull your car over unless you have violated the law, you would be wrong. The constitutional standard for a vehicle stop is "reasonable suspicion"--that is, "a particularized and objective basis for suspecting the particular person stopped" has violated the law. "Reasonable" does not mean correct. The Fourth Amendment allows for error. The officer can be wrong but as long as the mistake is objectively reasonable, the stop will be upheld as constitutionally valid.
Subsequent arrest for observed violationsAdditionally, if, as a result of the stop, the police find themselves in a position where they can make additional observations such as smelling alcohol on your breath, seeing contraband etc., then an arrest based upon those observations will be constitutionally sound. However, the police may not prolong the stop to develop probable cause, observation of another crime must be apparent within a reasonable period of time.
So, as long as the officer can articulate a reasonable basis for an erroneous belief that a driver has violated the law, an actual violation isn't necessary. A reasonable, though mistaken, belief that the law has been violated will not invalidate a stop.
What does this mean?What does that mean to you? Obviously, if you have been drinking, you can't do anything about the smell of alcohol on your breath or if you have been smoking, the lingering aroma of marijuana in the air will be apparent long after the smoking is over. However, contraband should never be in plain view in the console, the drink holder or on the seat. Don't make your arrest any easier than it has to be. Nothing should ever be in plan view and never voluntarily consent to a search.
AuthoritiesNorth Carolina v. Johnson, North Carolina Supreme Court, 8/18/2017
Heien v. North Carolina 574 U. S. ____ (2014)
State v. Bullock, 785 S.E. 2d 746 (NC App 2016)