Free Consent, governed by Sections 13-22, requires agreement without vitiating elements. Valid consent requires genuine agreement without coercion, undue influence, fraud, misrepresentation, or mistake. Coercion (Section 15): Pressure through threat causing person to contract unwillingly. Elements: Threat of wrongful act; threat induces consent. Undue Influence (Section 16): Improper pressure by person in confidence relationship. Types: Actual (proves dominance) and Presumed (certain relationships like trustee-beneficiary). Fraud (Section 17): Intentional misrepresentation inducing contract. Requires: Statement of false fact; knowledge of falsity; intent to induce; reasonable reliance; resulting damage. Misrepresentation (Section 18): False statement of fact without fraudulent intent. Innocent misrepresentation: No fraudulent intent but induces contract; voidable contract. Mistake (Sections 20-22): Bilateral mistake (both parties mistaken about fact material to contract) renders contract void; unilateral mistake (only one party mistaken) does not void contract unless other party knew. Case law: Allcard v. Skinner on undue influence establishes presumption in certain relationships. For accountants, understanding consent vitiating factors critical for engagement letter validity. Exam tip: Identify specific vitiating element; apply corresponding section; determine contract voidability/nullity.