The question emphasizes the role of Congress and the scope of its powers. In Morrison the Court approved a very complex hybrid of roles created by Congress. No written comment. Comment on Q 5. Control of evidence.
Admission of evidence seems to fall in the center of judicial functions.
Yet, Congress enters into the matter of governing evidence in all kinds of ways. For example, consider the Federal Rules of Evidence. Control of penalties. This aspect appears to interfere with the independent role of both attorneys and judges in carrying out their roles. See the related discussion in Morrison , Part V. Comment on Q 6.