Slate’s wonderful “Explainer” series had an informative article detailing your rights while riding the trains (or buses) in New York and D.C. “Are Subway Searches Legal?” This is a particularly relevant topic given the current state of paranoia:
Depends on how it’s done. The Fourth Amendment protects people from “unreasonable searches or seizures.” As a general rule, the government can’t search your baggage without a reason to believe you’re a criminal. But according to legal precedent, a random search is acceptable if it fulfills special needs like public safety. If New York’s subway screenings are challenged in court, the city’s lawyers could argue that the program’s primary purpose is to protect the city from terrorism.
Unless a judge agrees that they fulfill a special need, the screenings will be on shaky legal ground. In 2000, the Supreme Court ruled that a roadblock used to screen drivers for drug crimes was unconstitutional, since its primary purpose was to apprehend drug traffickers. On the other hand, roadblocks that screen for drunk drivers have been deemed OK, since they promote highway safety. (The court did say in the 2000 ruling that “a roadblock set up to thwart an imminent terrorist attack” would almost certainly be constitutional.)
The key legal point here seems to be that such an extreme curb on privacy rights has to come with both a sunset clause and a geographical constraint:
Let’s assume the courts believe the subways searches are an effective deterrent for terrorism and that the recent subway bombings in London make them reasonable. Then a judge would have to consider whether the scope and duration of the searches is appropriate. The first random subway screenings occurred last summer in Boston during the Democratic Convention. A district court ruled that searches on trains that ran beneath the convention center were acceptable since they took place in a restricted area for a limited amount of time. The New York City searches, though, are taking place all over the system and seem to be of open-ended duration.
The judge must also consider how individuals are selected for screening. If police officers have too much discretion, they might single out certain kinds of people for “random” searches. To prevent profiling, cops are sometimes given a strict formula—in Boston, for example, every 11th passenger was pulled aside at some commuter rail stations. The NYPD says “numerical criteria” are being used, but spokesmen also say that large or suspicious-looking bags can be red flags.
