[1] Hilton established the fundamental basis for the recognition and enforcement of foreign judgments in the United States,[2] remaining "the most detailed exposition of any American court" on this principle.

In finding that there was no applicable treaty or domestic statute from which an answer could be derived, the Court determined that it was incumbent on the judiciary to ascertain the law, based on guidance from "judicial decisions, from the works of jurists and commentators, and from the acts and usages of civilized nations."

Therefore, based on the notion of reciprocity derived from international comity, U.S. courts should similarly examine the merits of any judgment prior to ruling on its enforcement.

The Court's opinion is notable for drawing heavily from international legal sources, specifically the laws and practices of over a dozen nations all over the world regarding the recognition and enforcement of foreign judgments.

In France, and in a few smaller States — Norway, Portugal, Greece, Monaco, and Hayti — the merits of the controversy are reviewed, as of course, allowing to the foreign judgment, at the most, no more effect than of being prima facie evidence of the justice of the claim.