Imagine the following scenario: You're driving along one fine evening, pretty thoroughly drunk, and ram your car through police tape and into a barricade. Suppose further that the barricade you've smashed into is in front of the White House. For good measure, let's add that the police tape you broke was marking off an active crime scene - an ongoing bomb investigation, which you've now dangerously disrupted.

The cops quickly approach your car. What are your chances of avoiding arrest, or worse?

Oh wait. I forgot to mention that you're a Secret Service agent. So it turns out you don't get shot, or Tased, or roughed up, or slapped in jail, or even detained. You just go home.

Precisely this scenario unfolded on March 4, with two seemingly intoxicated Secret Service agents crashing into a barricade at the east entrance to the White House grounds, nearly running over a suspicious object that agents on the scene were in the course of investigating as a possible bomb.

What should a large group of bystanders do if they see a handful of attackers unjustly assaulting and tormenting an unarmed individual?

The answer seems obvious: come to the victim's aid by disarming and overpowering the attackers.

But on November 14, when UCLA student Mostafa Tabatabainejad was assaulted in the university library, about 50 shocked and angry students stood by, protesting and shouting but not intervening, though the assailants were much fewer in number and were armed only with nonlethal weapons.

Why didn't the students intervene? Because the assailants were campus police.