Definition - What does Controlling Law mean?
A controlling law is a law of a particular state that is used as an authority for certain legal issues, such as contracts or other documents, including trusts. Controlling laws are often used to settle disagreements or disputes when there are conflicting opinions on legal matters. Sometimes, different states may have different laws, and entities will choose which state's law they will use as a controlling law in a contract or other agreement.
Justipedia explains Controlling Law
Different states can have different policies on certain subjects. So, if two or more entities from different states are entering into a contract, there can be dispute as to which state's rules they should use. In such circumstances, the two entities can use one state's laws as a controlling law. They can then set up a contract that includes the law as the controlling law, and then their contract can be bound to that law when it comes to settling disputes related to it.