7. Concurrent Jurisdictions.—
There is no doubt that Congress has the power to make all crimes committed within the admiralty jurisdiction punishable in the federal courts but it has not done so and is not likely ever to so enact. Neither is it likely ever to assert an exclusive jurisdiction over all or any such crimes except as may be in violation of a purely federal enactment. Where this exclusive jurisdiction has not been asserted, either in terms or by necessary implication, state laws are not superseded by federal, and the same act may be punished as an offense against the United States and also as an offense against the State; it may thus be within the jurisdiction of both federal and state courts or the one may have jurisdiction of it under one aspect and the other under a different phase. The rule of comity is the same as in civil cases; where there is concurrent jurisdiction, the court which first obtains it, will continue to act to the exclusion of the other. Where the defendant obtains an acquittal in one court of concurrent jurisdiction, the judgment is a bar to a subsequent trial in the other, since he is not subject, for the same offense, to be twice put in jeopardy of life or limb.