Discovery is termed a procedural rather than a substantive matter (an ironic use of language, since rules that affect the procedure of the law often have more profound effects than rules that affect the substance of the law). ... Discovery is meant to help the parties to find the truth and properly prepare their cases.

Are rules of evidence substantive or procedural?

Because the rules of evidence are procedural law, the Federal Rules of Evidence are applied in federal court Federal Rules of Evidence are applied in federal court even where state law would normally be applicable and vice versa.

What is the difference between procedural rules and substantive rules?

Substantive law establishes the rights and obligations that govern people and organizations; it includes all laws of general and specific applicability. Procedural law establishes the legal rules by which substantive law is created, applied and enforced, particularly in a court of law.