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 Arizona, as in other states, the issue of which jurisdiction's laws apply to a lawsuit or dispute is governed by the principles of conflict of laws, also known as choice of law. When a case involves parties or elements from different states or jurisdictions, Arizona courts will analyze various factors to determine which state's laws should govern the dispute. These factors may include the location where a contract was signed or performed, the domicile or residence of the parties, the place where a tort was committed, and the jurisdiction with the most significant relationship to the case. Arizona courts will also respect and enforce choice of law clauses in contracts where parties have agreed in advance to be governed by the laws of a particular jurisdiction. However, such clauses must be the result of fair dealing and not contravene public policy. In cases involving federal law, federal courts may apply federal common law or the relevant state law, depending on the nature of the legal issue. The determination of applicable law is a complex process that often requires careful legal analysis and consideration of multiple legal principles.