Article III § 2 clause 2:
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.
This clause indicates whether each of the "cases" and "controversies" mentioned in Article III § 2 clause 1 are to acquire the attention of the "supreme Court" through original jurisdiction or through appellate jurisdiction. In cases in which ambassadors, consuls, etc., are involved, or in which one of the States is a party, the case goes directly to the supreme Court. All other cases must appear first in a lower court, and get the attention of the supreme Court only through the appeals process. — We find nothing objectionable about this arrangement, so we’ll say nothing more about it at this time.
Article III § 2 clause 3:
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.
This clause specifies that all criminal trials – excepting "Impeachment" – must be "by Jury". It specifies that the original trial – as distinguished from a case taken to the appeals level – must take place in the State where the purported crime happened. — We find nothing inherently wrong with this arrangement. There may be big problems with the way it’s being implemented in our day, but we’ll not attempt to address that issue at this time, for the sake of keeping this survey to a reasonable length.