This Chapter examines valuation within legal and regulatory contexts, where financial analysis intersects with evidentiary, procedural, and compliance frameworks. It analyzes three principal domains—litigation, transfer pricing, and antitrust—each requiring tailored methodologies grounded in causation, comparability, and legal standards. The discussion highlights how “but-for” analysis, rigorous documentation, and regulatory alignment transform valuation from market-based estimation into admissible expert evidence. By bridging economics, law, and governance, the Chapter equips practitioners to construct valuations that are not only technically sound but also defensible under judicial and regulatory scrutiny.