Arkansas court rules that Mormonism is not Protestantism

The Arkansas Court of Appeals recently handed down an unusual ruling in which a man was held in contempt for involving his children in the LDS Church. Actually, it's not as dramatic as it sounds. When Joel and Lisa Rownak divorced in 2005 they agreed that their two children would be raised "in the Protestant faith." Since this agreement was entered as part of the divorce decree, it was enforceable by the court.  Subsequent to their divorce, Joel Rownak converted to Mormonism and involved his two sons in his new faith, including baptizing one of the boys. Rownak made several free speech arguments, but the Arkansas court still found in contempt of the decree. The court relied heavily on the fact that Rownak himself had asked for the language to be placed in the divorce decree.
The interesting part of this case, as it relates to the Mormon Church, is the court's discussion of whether the Church of Jesus Christ of Latter-day Saints was a Protestant church. The court noted:

Based upon testimony by appellant’s wife, a statement by the president of LDS that was publicized on the church’s website, and testimony by appellant, the court found the LDS church not to be a Protestant faith and found that appellant had promoted the LDS faith to his sons.

Ark. App. CA08-193 p. 4. The question of whether Mormons are Protestants is mildly interesting, but it's fairly clear cut. The Arkansas court didn't seem to have much trouble coming to its conclusion. It would be more interesting if the divorce decree had required the children to be brought up "in the Christian faith." Then you would have a U.S. court attempting to determine an issue about which there is significant disagreement among various denominations. What sources would a court consult in determining whether Mormonism is part of Christianity? Would a court consult the LDS.org website, like the Arkansas court did on the Protestant issue? Or would the court instead rely on other religious authority outside of the LDS Church? And is even proper for a court to determine such controversial issues?
As much as I'd like to see the outcome of such a case, it probably isn't the sort of dispute that a court should resolve. In the Arkansas case there really wasn't much of a dispute over whether Mormonism was Protestantism. But it still raises some significant constitutional questions. On this topic UCLA Law Professor Eugene Volokh opined:

I think there are substantial limits on the enforceability of such contracts. The church property cases held that courts generally can't make theological decisions, such as which claimant's views are closer to orthodox (with a small "o") Presbyterianism; and I think the logic extends also to the interpretation of contracts, wills, and trusts that call for such decisions. Nor can courts avoid this constitutional barrier by trying to figure out what the majority of members of a religion thinks (hard to do reliably, plus it assumes the conclusion of who constitutes "members of a religion," and it privileges majority denominations within a religious group over minority denominations). And courts usually can't avoid the constitutional barrier, I think, by asking what the parties intended the term to mean — the best test of a word's intent is usually the word itself, and that is the very thing that calls for theological decisionmaking.

The Arkansas Court of Appeals' decision is available here.