U.S. Constitution, Article III, Sec. II extends to the federal courts: “The judicial Power shall extend to all Cases, in Law and Equity, arising under this Constitution, the Laws of the United States, and Treaties made, or which shall be made, under their Authority; to all Cases affecting Ambassadors, other public Ministers and Consuls; to all Cases of admiralty and maritime Jurisdiction; to Controversies to which the United States shall be a Party; to Controversies between two or more States; between a State and Citizens of another State; between Citizens of different States; between Citizens of the same State claiming Lands under Grants of different States, and between a State, or the Citizens thereof, and foreign States, Citizens or Subjects.” [emphasis added]
Since international law cases in the US are treated as regular cases within the federal system they can be found in the usual federal court reporters and databases. For assistance in finding them in the UCONN Law Library see UCONN Law Library LibGuide to Sources of Federal United States Law.
Coming soon you will be able to to use i.lex: The Legal Resarch System for International Law in U.S. Courts (ASIL) - a freely available database to help you identify and understand how international law is interpreted and applied by U.S. Courts at both the federal and state level.
There is also a print series (actually multiple series) which collect U.S. cases involving international law:
Each international court or tribunal has an online site where you can find the case decisions and, in some cases, the preliminary documentation as well.
High Courts in most jurisdictions have their own websites on which you can find decisions and other court documents. While some of these sites have an English version, remember that most often they will be only in the official languages of that jurisdiction and/or the non-English version will have more information and materials on it.