The Vermont Workmen's Compensation Act provides that a workman hired within the State shall be entitled to compensation even though the injury was received outside the State. Employers who hire workmen within this state to work outside of the state may agree with such workmen that the remedies under the provisions of this chapter shall be exclusive as regards injuries received outside this state by accident arising out of and in the course of such employment and that every contract of employment made within the State shall be presumed to have been made subject to its provisions, unless prior to the accident an express statement to the contrary shall have been made, in writing, by one of the parties. Neither D nor P filed a statement declining to accept any provision of the Vermont Act. The New Hampshire Act provides that the employer shall become subject to the workmen's compensation provisions of the Act only by filing a declaration to that effect and that even if the declaration is filed, the employee may, subsequent to the injury, still elect either to claim compensation or to sue for damages at common law as modified by the employers' liability provisions of the Act. D filed in New Hampshire the declaration provided for by its statute. P was a Vermont resident working for D, a Vermont employer in New Hampshire when P was killed. P's wrongful death action was removed to federal district court on the ground of diversity of citizenship. D, invoking the full faith and credit clause of the Federal Constitution, set up as a special defense that the action was barred by provisions of the Vermont Compensation Act; that the contract of employment had been entered into in Vermont, where both parties to it then, and at all times thereafter resided; and that the Vermont Act had been accepted by both employer and employee as a term of the contract. Both the district court and the court of appeals concluded that the Vermont Workmen's Compensation Act, which prohibited the common law action, did not apply. The New Hampshire court applied New Hampshire law, and P got the verdict. The appeals court affirmed. D appealed.