The legality of random subway searches
GapersBlock also notes the Slate's Explainer Friday looked at the same topic. Some of its conclusions:
"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.)"
This is uncharted territory. It will be interesting to see if a challenge is made to the New York initiative.