In Cox v. Louisiana (1965) 379 U.S. 559, the police chief and other local officials told civil rights demonstrators that they could demonstrate across the street from a courthouse, a location 101 feet from that building. The demonstrators proceeded within the parameters of this advice, but were subsequently convicted of violating a law barring picketing ?in or near" a courthouse. ( Cox, supra, 379 U.S. 559.) In Raley v. Ohio (1959) 360 U.S. 423, the chairman of the Ohio Un-American Activities Commission told four people being questioned by the Commission that they had a right to rely on a state constitutional privilege against self-incrimination. The state Supreme Court later held that the four were presumed to know that under Ohio law an immunity statute had deprived them of the privilege. In both Cox and Raley the Supreme Court held that to affirm the convictions "would be to sanction the most indefensible sort of entrapment by the State--convicting a citizen for exercising a privilege which the State clearly had told him was available to him." ( Raley v. Ohio, supra, 360 U.S. at p. 438; Cox, supra, 379 U.S. at p. 571). In the third case, United States v. Pennsylvania Chem. Corp. (1973) 411 U.S. 655, the Supreme Court applied estoppel to overturn a corporate conviction for discharging industrial refuse into a river, in violation of a federal statute. The Supreme Court concluded that the corporation could rely on the Army Corps of Engineers' conflicting interpretation of its regulation on the subject because it was "the responsible administrative agency under the statute, and the 'rulings, interpretations and opinions of the Corps ..., while not controlling upon the courts by reason of their authority, do constitute a body of experience and informed judgment to which ... litigants may properly resort for guidance.' " ( Id. at p. 674.)