After Carol Anne Bond discovered that her husband had impregnated her best friend, the Pennsylvania microbiologist took revenge by spreading toxic chemicals on her ex-friend's car door, mailbox, and door knob. The poisonous prank was mostly ineffectual, inflicting nothing worse than a minor thumb burn. Senior Editor Jacob Sullum says Bond's prosecution, the focus of a case the Supreme Court heard yesterday, could do a lot more damage. Defending its decision to make a federal case out of what sounds like fodder for a tabloid talk show, the Justice Department argues that treaties can give Congress new powers. Sullum says that theory threatens to destroy the constitutional division of authority between the states and the national government.