In context of conflict of laws, a referral is the proper translation for a so-called "Verweisung". In other words, whenever a forum court, under its own conflict of laws rule, is directed to consider the law of another state, the act of going to the other state's law is termed as "referral".
There are multiple definitions - click on the translation that matches your context.
the action or process of sending someone or something to another person or place for help, information, treatment, advice, a decision or to be dealt with, etc.
An entity cannot bill Medicare or Medicaid for services provided pursuant to an illegal referral.