[JLS]

Here is the relevant passage from Article III, Section 2

"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.

[PAR35]

This is also a relevant passage from Art. III

The judicial power shall extend to all cases, in law and equity, arising under this Constitution,

To the extent that there is any confusion in meaning between the two clauses, who gets to interpret it? The Federal Courts.