Uniform Commercial Code (UCC): Key legislation governing negotiable instruments (Article 3) and secured transactions (Article 9) if the note is secured. Provides framework for creation, enforcement and transfer of promissory notes.

Truth in Lending Act (TILA): Federal law requiring specific disclosures in consumer credit transactions, including clear disclosure of Annual Percentage Rate (APR) and other key lending terms.

State-Specific Laws: Individual state regulations governing promissory notes, including interest rate limitations (usury laws), statute of limitations for enforcement, and recording requirements for secured notes.

Federal Reserve Regulations: Including Regulation Z which implements TILA and sets requirements for consumer credit disclosures and transaction documentation.

Fair Debt Collection Practices Act (FDCPA): Federal law governing debt collection practices, relevant if the promissory note becomes subject to collection efforts.

Statute of Frauds: Legal doctrine requiring certain contracts to be in writing and signed to be enforceable, including specific requirements for written agreements and signatures.

Bankruptcy Code: Federal laws governing bankruptcy proceedings, affecting enforceability of promissory notes and priority of claims in bankruptcy situations.