Limits on the Supreme Court's Rule-Making Power

Limitations are provided for by the Constitution:

[1] The rules shall provide a simplified and inexpensive procedure for the speedy disposition of cases,
[2] The rules shall be uniform for all courts of the same grade, and
[3] The rules shall not diminish, increase, or modify substantive rights. (Art. VIII, Sec. 5[5], Constitution).

In determining whether a rule prescribed by the Supreme Court, for the practice and procedure of the lower courts, abridges, enlarges, or modifies any substantive right, the test is whether the rule really regulates procedure, that is, the judicial process for enforcing rights and duties recognized by substantive law and for justly administering remedy and redress for a disregard or infraction of them.

If the rule takes away a vested right, it is not procedural. If the rule creates a right such as the right to appeal, it may be classified as a substantive matter; but if it operates as a means of implementing an existing right then the rule deals merely with procedure. (Fabian vs. Desierto, G.R. No. 129742, September 16, 1998, 295 SCRA 40.)
Procedural and Substantive Rules; What is the test?

[1] It is whether the rule really regulates procedure, the judicial process for enforcing rights and duties recognized by substantive law and for justly administering remedy and redress for a disregard or infraction thereof.

[2] If it takes away a vested right, it is not procedural. If the rule creates a right such as the right to appeal – substantive.

[3] If it operates as a means of implementing an existing right – procedural.