The NYPD has begun searching straphangers' bags without any specific basis for believing them to be terrorists. The policy combines random checks (e.g., every tenth rider) with checks of those who are actually suspicuous (e.g., a bag with protruding wires and an accompanying ticking noise).
Naturally, I'm against the policy. It smacks of selling our rights for the illusion of safety. [Insert your favorite Ben Frankin quotation here.] Of course the NYPD defends the policy on the usual grounds: "The public understands we live in changed times," said the Commissioner.
So the age-old question returns. How much liberty are we surrendering, and for what benefit? The liberty interest seems pretty big to me. For many New Yorkers, the subway is the only way to get to and from work. It's the only practical way to visit much of the city. Therefore, anyone who cannot afford regular taxi fare now implicitly has no right to be free of searches of his person and effects.
The benefit is close to zero. Yes, we may deter a would-be subway bomber. But he can always blow up a nearby Starbucks and kill just as many people. It's like "the Club," which does not deter car theft but merely moves it from Clubbed cars to others. (And a murderer can of course blow up the checkpoint itself, like people do in Iraq and Israel, thereby turning a safety device into a death trap.)
The NYCLU has said it will likely sue. I think it should win.
P.S. Another interesting case is the right to travel anonymously on airplanes. See more here about a case in the Northern District of California challenging FAA requirements that air travellers show ID.