Personal Data Protection Act (PDPA): Singapore's primary data protection legislation that governs the collection, use, and disclosure of personal data. In regret letters, ensure proper handling of candidate's personal information and maintain application confidentiality.

Employment Act: Singapore's main employment law that sets out basic terms and conditions at work. For regret letters, ensure compliance with fair employment practices and Tripartite Guidelines on Fair Employment Practices (TGFEP).

Anti-Discrimination Laws: Laws preventing discrimination based on race, religion, age, gender, nationality, and disability. Ensure regret letter contains no discriminatory statements or implications.

Fair Consideration Framework (FCF): Guidelines ensuring fair employment opportunities for Singaporeans. Maintain proper documentation of hiring process and ensure compliance with FCF requirements in communication.

Defamation Laws: Laws protecting against false statements that harm reputation. In regret letters, stick to factual and professional communication, avoiding potentially defamatory statements.