Article 3, Section 2

Short Version -- This is a summary of the important issues covered in this section of the U.S. Constitution. 

• The judiciary decides cases arising under the Constitution and cases involving federal laws, treaties, and so forth.
• Cases involving ambassadors and states go directly to the Supreme Court for judgment.
• Other kinds of cases can go to the Supreme Court on appeal.
• Except for cases of impeachment, all crimes are tried by jury.
• Trials are held in the state where the crime was committed.

Long Version -- This is the text of the Actual U.S. Constitution. 

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.

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.