P was an engineer employed by D in Jefferson County, Alabama. While he was under a locomotive repairing the brakes, a defective throttle caused the engine to move forward and P was seriously injured. P sued D in Atlanta, Georgia, under §3910 of the Alabama Code of 1907, which makes the master liable to the employee when the injury is 'caused by reason of any defect in the condition of the ways, works, machinery or plant connected with or used in the business of the master or employer.' D filed a plea in abatement in which it was set out that §6115 of that Code also provided that 'all actions under said section 3910 must be brought in a court of competent jurisdiction within the State of Alabama and not elsewhere.' D claimed that to continue the suit in Georgia would be a denial so far as the rights of D are concerned, of full faith and credit to said public acts of the State of Alabama in the State of Georgia, contrary to the provisions of Art. 4, § 1 of the Constitution of the United States. A demurrer to the plea in abatement was sustained and the judgment for P was entered and affirmed by the Court of Appeals. The Supreme Court granted certiorari.