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.This also answers one of Edmund Randolph's problems with the Articles of Confederation, "that the foederal government could not check the quarrels between states".
In all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party, the supreme Court shall have original Jurisdiction. In all the other Cases before mentioned, the supreme Court shall have appellate Jurisdiction, both as to Law and Fact, with such Exceptions, and under such Regulations as the Congress shall make.
The Trial of all Crimes, except in Cases of Impeachment, shall be by Jury; and such Trial shall be held in the State where the said Crimes shall have been committed; but when not committed within any State, the Trial shall be at such Place or Places as the Congress may by Law have directed.
The flip side to the Supreme Court being the bastard stepchild of the three branches of government was the seeming inability for the Constitution to be enforced if the Congress and President happened to pass something that violated it. Edmund Randolph's Virginia Plan would have called for the Congress to veto any state laws that violated the Constitution, and coming on the heels of Madison's speech calling for national unity (link: AISX), originally passed without a hitch. (Benjamin Franklin added a proviso also allowing Congress to veto any state laws contradicting treaties the US had signed.) But what about the national Congress?