Paul Sperry of the Hoover Institution comments here about the foolishness of scrutinizing mass transit passengers only on a random basis. Excerpt:
Once an Islamist suicide bomber is sitting next to you on the train, your chances of escape are slim. The only solution is for the police to stop him well before he boards your car. But with the system as it stands, that terrorist could easily slip in through the numerical window of random security screening. By not allowing police to profile the most suspicious train passengers - young Muslim men who fit the indicators above - Mr. Bloomberg and other leaders not only tie one hand behind law enforcement's back, but they also unwittingly provide terrorists political cover to carry out their murderous plans. Call it politically correct suicide.
Read the whole thing; it's short, pithy, persuasive, and a little scary.
UPDATE: This New York Times piece discusses what can happen when police engage in profiling and use deadly force as part of that process. The result in this case was tragic but the right thing to do, in my view.