I agree, but will add that in the state court decisions I did review in which the state courts stated the trial court lacked the authority to compel a spouse to join in filing a joint return, they did it based on reasons of state law, not based on the federal Constitution or any federal law. So I'm not even seeing a conflict for the Supreme Court to resolve. Of course the Supreme Court could agree to hear it even without a conflict if it though the Constitutional argument compelling enough warrant its review.

