When there is more than one state, or more than one jurisdiction (state court, federal court) with a significant relationship to the parties and circumstances involved in a lawsuit or dispute, the question may arise as to which state or jurisdiction’s laws will govern the lawsuit or dispute. The body of law that determines what law governs a dispute is called conflict of laws and consists of legal principles courts use to determine which state or jurisdiction’s law applies—unless the parties to a dispute have agreed (usually in a contract) on what law will apply.

In Missouri, as in other states, when a lawsuit or dispute involves multiple states or jurisdictions, the determination of which state or jurisdiction's laws will apply is governed by the principles of 'conflict of laws' or 'choice of law.' These principles are designed to resolve issues when there is a disagreement over which jurisdiction's laws should be used to adjudicate a matter. Missouri courts will consider various factors, such as the location where a contract was signed, where a tort occurred, the residency of the parties involved, and the jurisdiction with the most significant relationship to the dispute. Additionally, Missouri recognizes and enforces choice of law clauses in contracts where parties have agreed in advance to the application of a particular jurisdiction's laws. However, such clauses must be the result of a fair negotiation process and not be contrary to public policy. In cases without a contractual agreement on jurisdiction, Missouri courts will apply conflict of laws rules to ensure that the most appropriate and relevant legal framework is used to resolve the dispute.