State Rules of Professional Conduct: State-specific ethical rules governing attorney conduct, including requirements for fee agreements, attorney fees, and attorney-client relationships. Each state bar maintains its own specific requirements.

ABA Model Rules: American Bar Association guidelines including Rule 1.5 (attorney fees), Rule 1.4 (client communications), and Rule 1.2 (scope of representation) that form the basis for most state professional conduct rules.

State Bar Guidelines: Specific requirements from state bar associations regarding contingency fee agreements, including maximum allowable percentages, required disclosures, and notifications to clients.

Federal Regulations: Federal laws affecting contingency fees, including Federal Tort Claims Act restrictions, Social Security Act fee limitations, and workers' compensation fee limitations.

State Consumer Protection Laws: State-specific laws protecting consumers, requiring clear disclosure of terms, cooling-off periods, and cancellation rights in legal service agreements.

State Contract Laws: Basic contract formation requirements, enforceability provisions, and statute of limitations considerations specific to the state where the agreement is executed.

Practice Area Regulations: Specific regulations governing fees in particular practice areas, such as personal injury fee limitations, medical malpractice fee caps, and class action fee rules.