Contracts Act 1950: The fundamental law governing contract formation and validity in Malaysia, ensuring the authorization letter meets basic contractual requirements of offer, acceptance, consideration, and intention to create legal relations.

Powers of Attorney Act 1949: Although not directly applicable to all authorization letters, this Act provides important principles regarding delegation of authority and the formal requirements for granting someone power to act on another's behalf.

Stamp Act 1949: Requires certain documents, including authorization letters, to be properly stamped to be admissible in court and legally enforceable. The authorization letter may need to be stamped depending on its nature and purpose.

Digital Signature Act 1997: Relevant if the authorization letter is to be executed electronically, providing legal recognition of digital signatures and their validity in Malaysian law.

Evidence Act 1950: Governs the admissibility of documents as evidence, including requirements for document authentication and verification, which is crucial for authorization letters that may need to be presented in legal proceedings.