delivered the opinion of the court.

This is an action to recover taxes paid 'under duress and protest, the plaintiff contending that the law under which the tax was levied is unconstitutional. A demurrer to the declaration was sustained by the Circuit Court. The tax is a tax of two cents upon each one thousand dollars of the plaintiff’s capital stock. Session Laws of Colorado, 1907, c. 211 (April 1, 1907). The plaintiff is a Kansas corporation. The greater part of its property and business is outside of the State of Colorado, and of the business done within that State but a small proportion is local, the greater part being commerce among the States. Therefore it is obvious that the tax is of the kind decided by this court to be unconstitutional, since the decision below in the present case, even if the temporary forfeiture of the right to do business declared by the statute be confined by construction, as it seems to have been below, to business wholly within the State. Western Union Telegraph Co. v. Kansas, 216 U. S. 1. Pullman Co. v. Kansas, 216 U. S. 56. Ludwig v. Western Union Telegraph Co., 216 U. S. 146. The defendant did not argue that 'the tax could be maintained,, but contended only that the payment was voluntary and that the defendant is not the proper person to be sued.

It is reasonable that a man who denies the legality of a tax' should have a clear and certain remedy. The rule being established that apart from special circumstances he cannot interfere by injunction with the State’s collection of its revenues, an action at law to recover back what he has paid is the alternative left. Of course we are speaking of those cases where the State is not put to an action if the citizen refuses to pay. In these latter he can interpose his objections by way of defence, but when, as is common, the State has a more summary remedy, such as *286 distress, and the party indicates, by protest that he is yielding to what he cannot prevent, courts sometimes perhaps have been a little too slow to recognize the implied duress under which payment is made. But even' if the State is driven 'to an action, if at the same time the citizen is put at a serious disadvantage., in the assertion of his legal, in this case of his constitutional, rights, by defence in the suit, justice may require that he should be at liberty to avoid those disadvantages by paying promptly and bringing suit on his side-1' He is entitléd to assert his supposed right on reasonably equal, terms. .Sée Ex parte Young, 209 U. S. 123, 146. If he should seek an injunction on the principle of . that casé and of Western Union Telegraph Co. v. Andrews, 216 U. S. 165, he would run the same risk as if he waited tó be sued.

In . this case the law, beside giving an action of debt to the State, provides that every corporation that fails to pay the tax shall forfeit its right to do business within the State until the tax is paid, and also shall pay a penalty of ten per cent, for every six months, or fractional, part of six months of- default after May 1 of each year. It may. be that the forfeitúre of the. right to do business would. not be authoritatively established except by a quo warranto provided for in a following section, but before" or •without, the proceeding the--effect of the forfeiture clause upon the "plaintiff’s subsequent contracts and business might be serious, (see Ludwig v. Western Union Telegraph Co., 216 U. S. 146), and in any event the penalty would go "on accruing during all the time that might be spent before, the validity of the defence could be ádjudged. As appears from the decision below, the plaintiff could have had no certainty of ultimate success, and we áre of opinion that it was not called upon to take the risk of having its contracts disputed and its business injured arid of finding the tax more or less nearly doubled in case it finally had to pay. In other -vvords, we are of opiniori that the pay *287 ment was made under duress. See Gaar, Scott & Co. v. Shannon, decided this day, post; p. 468.

The other question-is whether the defendant is liable to the suit. The defendant collected the money and it is alleged that he still has it. He was notified when he received' it that the plaintiff disputed his right. If he had no right,' as he had not, to collect the money, his doing so in the name of the State cannot protect him. Erskine v. Van Arsdale, 15 Wall. 75. See Virginia Coupon Cases, 114 U. S. 270. It is said that the money as soon as collected belonged to the State. Very likely it would have but for the plaintiff’s claim, assuming it to remain an identified trust fund; but the pláintiff’s claim was paramount to that of the State, and even if the collector of the tax were authorized to appropriate the specific, money and to make himself debtor for the amount, it would be inconceivable that the State should attempt to hold him after he had been required to repay the sum. Moreover it would seem that the statute contemplated the course taken by the plaintiff and provided against any difficulty in which the Secretary of State otherwise might find himself in case of a disputed tax. For it provides by § 6 that ‘ if it shall be determined in any action at law or in equity that any corporation has erroneously paid said tax to the Secretary of State,-’ upon the filing of a certified copy of the judgment the auditor may draw a warrant for the refunding of the tax and the state treasurer may pay it. We must presume that a judgment in the present action would satisfy the law.

Judgment reversed.