Ronald Elwell, a General Motors Corporation (GM) (defendant) engineering analyst, worked for GM for thirty years. During this time, he studied the safety of GM vehicles and would on occasion testify on GM’s behalf as an in-house expert witness in product liability actions. In 1991, after leaving GM’s employ and during a deposition taken by a plaintiff in a products liability case, Elwell gave testimony that was markedly different from that which he gave while he was an in-house expert. This testimony suggested that GM’s fuel system was inferior to other comparable automobiles. Shortly thereafter, Elwell initiated a wrongful discharge suit against GM in Michigan county court. GM counterclaimed and filed a motion for a preliminary injunction preventing Elwell from consulting or discussing confidential information relating to GM that Elwell learned during his employment. The following year, GM and Elwell entered into a settlement, stipulating the injunction would be permanent, but that if Elwell was compelled by a tribunal to testify, that he would not be liable for a violation of their settlement agreement. In 1991, Beverly Garner was killed in a Missouri highway accident when the GM automobile in which she was a passenger caught fire. Garner’s sons, Kenneth and Steven Baker, initiated a wrongful death action in Missouri state court and sought to subpoena Elwell. GM objected, and the court allowed the Bakers to subpoena Elwell, finding that (1) blocking Elwell’s testimony would violate Missouri’s public policy, and (2) that the injunction could be modified both in Michigan and in any other state. As a result of this testimony, the Bakers received $11.3 million in damages. On appeal, the Eighth Circuit reversed, finding that the Full Faith and Credit Clause of the Constitution required the trial court to uphold the injunction. The Bakers appealed, and the United States Supreme Court granted certiorari.