US SUPREME COURT DECISIONS

If the car is moving on a railroad engaged in interstate commerce, it is subject to the provisions and penalties of the Safety Appliance Act, although engaged at the time in intrastate commerce. United States v. Southern Ry., 222 U. S. 20.

The principle that an act may constitute a criminal offense against chanrobles.com-red

Page 236 U. S. 440

two sovereignties, so that punishment by one does not prevent punishment by the other, only relates to cases where both sovereignties have jurisdiction over the act. It has no application where one of the governments has exclusive jurisdiction of the subject matter, and therefore has the exclusive power to punish.

Under the federal Constitution, the power of Congress to regulate interstate commerce is such that, when exercised, it is exclusive and ipso facto supersedes existing state legislation on the same subject.

Congress may so circumscribe its regulations in regard to a matter within its exclusive jurisdiction as to occupy only a limited field and leave a part of the subject open to incidental legislation by the states; but the Safety Appliance Act extended to the whole subject of equipping cars with safety appliances, to the exclusion of further action by the states.

The Indiana statute requiring railway companies to place grab-irons and hand-holds on the sides and ends of every car having been superseded by the federal Safety Appliance Act, penalties imposed by the former cannot be recovered as to cars operated on interstate railroads although engaged only in intrastate traffic.

The facts, which involve the effect of the Federal Safety Appliance Act on state statutes relating to safety appliances on railroad cars used in interstate commerce, are stated in the opinion. chanrobles.com-red

Page 236 U. S. 444