Baggage Checks in NYC Subways -- Another Cosmetic Security Measure

The AP is reporting that police will begin random checking of people's bags on NYC subways:

Police will begin random searches of bags and packages carried by people entering city subways, officials announced Thursday after a new series of bomb attacks in London.

Passengers carrying bags will be selected at random before they pass through turnstiles, and those who refuse to be searched won't be allowed to ride, Police Commissioner Raymond Kelly said.

"We just live in a world where, sadly, these kinds of security measures are necessary," Mayor Michael Bloomberg said. "Are they intrusive? Yes, a little bit. But we are trying to find that right balance."

The announcement drew complaints from civil liberties advocates in a city where an estimated 4.5 million passengers ride the subway on an average weekday. The system has more than 468 stations — most with multiple entrances — and the flood of commuters hurrying in and out of stations during rush hour can be overwhelming.

Kelly stressed that officers posted at subway entrances would not engage in racial profiling, and that passengers are free to "turn around and leave." He also downplayed the possibility of bottlenecks at subway entrances.

That makes me feel better -- people are just free to leave, so the searching is fine.  I'm dashing this post off quickly, so I won't explore the legality of this.  But regardless of the legal issues, this seems to me to be a very silly policy.  It is another big waste of money and time, as well as a needless invasion of civil liberties -- all for a cosmetic security benefit.  There are 4.5 million passengers each day on the NYC subways.  What good could a few random checks do?  The odds of the police finding the terrorist with a bomb this way are about as good as the odds of being hit by lightning.   I doubt it will have much of a deterrent effect either. 

Also consider this from the story:

Kelly said passengers selected for searches will be approached by officers, who will ask them what they are carrying, and request them to open their bags. If an officer looking for explosives finds some other form of contraband, police said that person would be subject to arrest. 

Does this mean that if the police find illegal drugs that they will arrest people?  It isn't clear what categories of "contraband" are included in this statement.   

A more effective strategy might be to use bomb sniffing dogs, as this would better prevent the police from conducting searches for drugs or things other than bombs.  But even the use of dogs, with the sheer numbers of subway passengers, does not strike me as very effective either.