One of the ladies I work with, her husband is an officer in SC. He said the same thing as SRGN. He said they will many times get in behind someone and it only takes a block or two for them to do something that gives them cause to pull the vehicle over. He said most people who aren't doing any thing don't focus all their attention on the mirror or look for a place to turn off right away. The criminals will do one of these almost every time.