“ For while, on a writ of error to a state court, our province ordinarily is only to inquire whether that court has erred in the decision of some Federal question, it does not follow that where, pending the writ, a statute of the state or a decision of its highest judicial tribunal intervenes and put an end to the right which the judgment sustains, we should ignore the changed situation, and affirm or reverse the judgment with sole regard to the Federal question. ”

“ The intervening decision does not in itself annul the judgment for the fee or prevent its enforcement, and so does not render the Federal question a moot one, unless it operates to place upon us the duty of reversing the judgment without regard to the merits of that question.
The case is still pending. The right to the attorneys' fee is still sub judice. It depends entirely upon the statute, and the highest court of the state has pronounced the statute invalid under the state Constitution. How, then, can we sustain the right or give effect to the statute? ”

“ Instead of being an obstacle to granting any effectual relief to the plaintiff in error, that decision constitutes in itself an all-sufficient ground for relieving it from the attorneys' fee, independently of the Federal question presented on the record; and for the reasons before stated we think it becomes our duty to vacate the judgment, so that the state court may apply the decision by awarding a new judgment in conformity therewith. ”