Natural justice before the Appellate Tribunal governs its procedure, with civil court powers for evidence, defaults, and enforcement. The Appellate Tribunal is not bound by the Code of Civil Procedure, 1908, but must follow natural justice and may regulate its own procedure under the GST law. It has civil court-like powers to summon persons, require documents, receive affidavit evidence, requisition public records, issue commissions, and deal with default or ex parte orders. Its orders are enforceable as civil court decrees, and proceedings are treated as judicial proceedings for specified penal law purposes, with the Tribunal deemed a civil court for certain criminal procedure provisions.