It’s pretty remarkable: If a contract provides that it is to be decided under, say, English law (or Mexican law), a judge wouldn’t be able to apply that law (see subsection C) — on penalty of impeachment. If a court is trying to decide whether an immigrant was another immigrant’s adoptive parent, a question that now reasonably turns on the law of the place of adoption, it would no longer be able to look to the foreign country’s statutes in determining that (see subsection B(1)). If a court is dealing with a tort claim based on an injury that happened in Canada, and the normal choice-of-law rule would require reliance on Canadian law (understandable), that normal rule would be preempted.
Courts dealing with common-law or common-law based doctrines of contract, tort, and property law would at least be able to consider (see the exception in subsection E(2)) influential English court decisions in those areas, decisions that have often become important parts of American law (and Arizona law) — but not if the decisions are handed down after the effective date of the article, or if they are from Canada or Australia rather than Great Britain. See, e.g., 7200 Scottsdale Road General Partners v. Kuhn Farm Machinery, Inc., 909 P.2d 408 (Ariz. Ct. App. 1995) (noting that “The doctrine of frustration of purpose traces its roots to Krell v. Henry,  2 K.B. 740,” and discussing this leading case at considerable length). Plus it’s not clear whether even older decisions would be covered, since the exception applies only to principles “inherited from Great Britain”; post-Revolutionary English precedents aren’t exactly “inherited” from Great Britain. Properly ratified treaties, which Article VI of the U.S. Constitution, says are the supreme law of the land, are at least exempted (F(2)). But foreign decisions interpreting such treaties, such as treaties governing foreign service of judicial documents, can’t be cited even as influential.
Are such radical changes to longstanding Arizona law really sensible? There are sensible criticisms of the use of foreign law in interpreting the U.S. Constitution, though even Justice Scalia thinks that such use of foreign law — and not just pre-1787 English law — is acceptable in limited ways. But is it really sound to displace the many subconstitutional rules through which American courts have long tried to accommodate the reality that much commercial and personal life is international?
Here’s the state house version; the senate version is identical:
A. A court shall not use, implement, refer to or incorporate A tenet of any body of religious sectarian law into any decision, finding or opinion as controlling or influential authority.
B. A court shall not use, implement, refer to or incorporate any case law or statute from another country or a foreign body or jurisdiction that is outside of the United States and its territories in any decision, finding or opinion as either:
1. Controlling or influential authority.
2. Precedent or the foundation for any legal theory.
C. Any decision or ratification of a private agreement that is determined, on the merits, by a judge in this state who relies on any body of religious sectarian law or foreign law is null and void, is appealable error and is grounds for impeachment and removal from office.
D. This section applies to a federal court sitting in diversity jurisdiction.
E. This section does not apply to:
1. A statute or any case law developed in the United States and its territories that is based on Anglo-American legal tradition and principles on which the United States was founded.
2. A statute or any case law or legal principle that was inherited from Great Britain before the effective date of this article.
3. The recognition of a traditional marriage between a man and a woman as officiated by the clergy or a secular official of the matrimonial couple’s choice.
F. For the purposes of this section:
1. “Foreign Body” includes the United Nations and any agency thereunder, the European Union and any agency thereunder, an international judiciary, the International Monetary Fund, the Organization of Petroleum Exporting Countries, the World Bank and the Socialist International.
2. “Foreign Law” means any statute or body of case law developed in a country, jurisdiction or Foreign Body outside of the United States, whether or not the United States is a member of that body, unless properly ratified as a Treaty pursuant to the United States Constitution.
3. “Religious Sectarian Law” means any statute, tenet or body of law evolving within and binding a specific religious sect or tribe. Religious sectarian law includes Sharia Law, Canon Law, Halacha and Karma but does not include any law of the United States or the individual states based on Anglo American legal tradition and principles on which the United States was founded.
(For the “legislative findings,” see the linked-to document.) Oh, and I love the reference to the Socialist International, a source that would otherwise be very heavily cited by American courts.