 Ends justifies the means. It shocks me, but it doesn't surprise me. This is Michael Sierra Arevalo. He's an assistant professor in the Department of Sociology at the University of Texas at Austin and has spent years studying police culture. Arevalo says part of the reason police are so concerned with arming themselves with the newest technology and equipment is because of something he calls the danger imperative, which coincidentally is the title of his new book.