The Wednesday New York Times had this report about a court ruling on how to measure whether a defendant was selling drugs within 1,000 of a school:

  The question before the state's highest court, the Court of Appeals, was whether a man named James Robbins was guilty of selling drugs within 1,000 feet of a school - which carries a longer sentence - when he was arrested in March 2002 on the corner of Eighth Avenue and 40th Street in Manhattan and charged with selling drugs to an undercover police officer.
  The nearest school, Holy Cross, is on 43rd Street between Eighth and Ninth Avenues. How to measure? On foot, Mr. Robbins's lawyers argued, the school is more than 1,000 feet away from the site of the arrest, because the shortest route is blocked by buildings. But as the crow flies, the authorities said, it is less than 1,000 feet away.
  Law enforcement officials calculated the straight-line distance using the Pythagorean theorem (a2 + b2 = c2) measuring the distance up Eighth Avenue (764 feet) as one side of a right triangle, and the distance to the church along 43rd Street (490 feet) as another, to find that the length of the hypotenuse was - 907.63 feet.
  Lawyers for Mr. Robbins argued that the distance should be measured as a person would walk it because "crows do not sell drugs." But in a unanimous ruling, the seven-member Court of Appeals upheld his conviction and held that the distance in such cases should be measured as the crow flies.

  The opinion of the New York Court of Appeals is here. Thanks to HJB for the link.