US Supreme Court Garrity v. New Jersey 13

Decided January 16, 1967
   Court case number 13.  :)  Apparently, the case numbering scheme has gotten a lot more complex since the 60's.

   Garrity was a cop, and he was one of several who were being investigated by the New Jersey Attorney General for fixing tickets.  Each of the cops involved was interrogated, and prior to their interrogation each of them were advised of the following: (1) that anything he said might be used against him in any state criminal proceeding; (2) that he had the privilege to refuse to answer if the disclosure would tend to incriminate him; but (3) that if he refused to answer he would be subject to removal from office.

   In order to keep their jobs, they waived their rights.  They made incriminating statements, which were later admitted in court over their objections, and they were convicted.  They appealed their convictions.

   The US Supreme Court held that making it a condition of employment for a public servant that they waive a constitutional right is coercive, and that therefore the waiver of the right is not free and voluntary.  Statements obtained this way may not be used in a criminal proceeding, and the decision of the lower courts was reversed.