Privileges & Immunities (Article IV)

States cannot discriminate against nonresidents regarding fundamental economic activities without substantial justification.

Related Federalism & State Power rules

• PreemptionFederal law preempts conflicting state law expressly or implicitly when Congress intends to occupy the field.
• Dormant Commerce ClauseStates may not discriminate against or unduly burden interstate commerce absent legitimate local purpose.
• State Taxation of Interstate CommerceState taxes on interstate commerce must be nondiscriminatory and fairly related to services provided.

Part of Constitutional Law on Core Legal Rules — foundational MBE-tested principles with primary-source citations.