When Can the Police Frisk the Passenger of a Car for Weapons?

In the case of Arizona v. Johnson, the United States Supreme Court addressed the following

question:

Whether a police officer may lawfully frisk a passenger in a vehicle stopped for a minor traffic infraction when the officer has no reason to believe that the passenger has committed, is committing, or is about to commit a crime, but nevertheless reasonably suspects the passenger to be armed and dangerous?

An article that I posted on my website, Federal Criminal Lawyer: Frequently Asked Questions, examines the facts of the Johnson case as well as the reasons why the Supreme Court ruled that such a frisk is lawful.