That's what happened in Ghassemi v. Ghassemi. The judge's reasoning, as quoted by the appellate court:
This court exercising its powers vested from the state, this court will not recognize any document, decree, judgments[,] statutes or contracts and will not give comity ... and no validity whatsoever from the country of Iran [s]ince that country has been declared by itself and by its leader to be an enemy of the United States. The United States has had no diplomatic relations with that country for 28 years, and they are not a signatory to the Hague Convention with respect to marriages.
Under the court's reasoning, all couples married in Iran would have been unmarried for all legal purposes (or at least for purposes that require their going to court). They wouldn't have been able to inherit under the laws of intestate succession, they couldn't have called on the standard legal procedures for property settlement under divorce, they couldn't have sued to obtain various insurance benefits that were available only to married couples, and so on. And for no reason other than that the leaders of the country in which they were married are enemies of the United States.
The ruling would have even applied to American citizens who were married in Iran, either because they went there to get married (consider an American who goes to Iran to marry an Iranian, or two Americans who go to Iran to be married in front of their families) or because they married there and then moved to the U.S. and became U.S. citizens. Nor can the reasoning be based on the argument that the parties should have known of this consequence when they chose to marry in a country that was an enemy of the U.S. (an unpersuasive argument even when the fact support it): The claimed marriage here took place in 1976, when Iran was a U.S. ally.
Fortunately, the Louisiana Court of Appeal has just reversed this decision. "It would be a questionable policy indeed to base the status of private individuals on the fluctuation of international relations," the court concluded. I would add that it's equally questionable to base the status of private individuals — a status that is of great importance to them in their lives in the U.S., and to American governments in administering American law — on the poor behavior of the leaders of the country in which they were married.
Indeed, sometimes the bad behavior of a country's leaders does inevitably harm innocent citizens of this country. But that is something to be regretted, not something to be added to with no reason. And there really is no reason to add to it here: For instance, as the appellate court pointed out, there's no inherent problem with relying on or authenticating Iranian documents (as opposed to the potential problems with relying on or authenticating any foreign documents, which chiefly turn on country attributes other than its hostility to the U.S.).
In any case, this was a poor decision by the trial court, and a good decision by the Louisiana Court of Appeal.