The following opinion was filed March 6, 1928:
Owen, J.On July 24, 1920, and within one year after the death of Patrick Cudahy, deceased, the executors of his estate paid to the treasurer of Milwaukee county the sum of $222,237.49, the estimated amount of the inheritance tax due from the estate to the state of Wisconsin and to the county of Milwaukee. This payment was accompanied by a formal protest. Thereafter, and in due course, the amount of the inheritance tax was determined by the county court of Milwaukee county. The tax as so determined included a tax upon certain gifts made by said Patrick Cudahy to his relatives within six years of his death. In determining-such tax the county court gave full effect to the statute then existing (sec. 72.01 (3), Stats. 1925), which required every gift made within six years prior to the death of the donor to be construed to have been made in contemplation of death. The supreme court of the United States declared this statute unconstitutional in the case of Schlesinger v. Wisconsin, 270 U. S. 230, 46 Sup. Ct. 260. This action was prompted by that decision.
We find at least two insuperable obstacles to plaintiffs’ *244recovery: first, the payment of the tax was a voluntary payment; and second, the determination of the tax by the county court is res adjudicata and cannot be attacked in this action.
Under our law the inheritance tax is determined by the county court, upon which court is conferred jurisdiction to hear and determine all questions arising under the provisions of the inheritance tax laws. Sec. 72.12, Stats. All taxes imposed are due and payable at the time of the transfer, which occurs at the death of the grantor. Sec. 72.05. If the tax is paid within one year from the accruing thereof, a discount of five per centum is allowed. If such tax is not paid within eighteen months from the accruing thereof, interest is charged at the rate of ten per centum per annum from the time the tax accrued, “unless by reason of claims made upon the estate, necessary litigation or other unavoidable cause of delay, such tax shall not be determined and paid as herein provided, in which case interest at the rate of six per centum per annum shall be charged upon such tax from the accrual thereof until the cause of such delay is removed, after which ten per centum shall be charged.” Sec. 72.06.
The tax in this case was paid within one year after the death of the grantor by the executors of the estate. As a result thereof the estate was allowed a discount of five per centum. There was no threat made to collect the tax. There was no coercion by the state acting through any tax collector. It was evidently paid for the purpose of procuring the five per centum discount.
It is fundamental that in order to constitute an involuntary payment there must be some form of coercion. This coercion may be in the form of a threat on the part of the tax collector to levy on the goods of the taxpayer if he does not pay, or it may be in the nature of heavy penalties visited by law upon the taxpayer in case of nonpayment. In this case there was no threat on the part of any one to make *245levy, or pursue any other remedy for the purpose of making-collection of the tax. If we find any coercion here it must be due to the penalties resulting from a failure to pay the tax. Whatever penalties result from such failure will be found in sec. 72.06, already referred to. That provides for interest at the rate of ten per centum per annum if the tax is not paid within eighteen months from the date of the transfer. That rate of interest does not obtain, however, if, by reason of claims made upon the estate, necessary litigation, or other unavoidable cause of delay, such tax shall not be determined, but in such case interest at the rate of six per centum per annum only shall be charged.
Sec. 72.08 provides for the refunding of taxes erroneously paid, “Provided, however, that all, applications for such refunding of erroneous taxes shall be made within one year from the payment thereof, or within one year after the reversal or modification of the order fixing such tax.” This plainly recognizes the right of an appeal from, an order of the county court fixing the amount of the inheritance tax chargeable against an estate. This right has frequently been invoked. State v. Thompson, 154 Wis. 320, 142 N. W. 647; Estate of Smith, 161 Wis. 588, 155 N. W. 109; Estate of Week, 169 Wis. 316, 172 N. W. 732; Estate of Ebeling, 169 Wis. 432, 172 N. W. 734; Estate of Stephenson, 171 Wis. 452, 177 N. W. 579; Estate of Schlesinger, 184 Wis. 1, 199 N. W. 951. An appeal from that order, conducted in good faith, certainly constitutes necessary litigation within the meaning of the provisions of sec. 72.06. Had the plaintiffs or others interested in the determination of the tax in the- Patrick Cudahy estate appealed from the order of the county court fixing the inheritance tax, there would have followed an interest charge of six per centum only. This is the only penalty that would have resulted from the nonpayment of the tax until it was finally and conclusively determined in orderly judicial proceedings. This is *246but the legal rate of interest provided for the withholding of any money which should be paid. We have been cited to no authority holding that a payment made to avoid the legal rate of interest constitutes an involuntary payment. The law could not tolerate such a rule. Business settlements would have no finality. Every note or other indebtedness could be paid under protest for the purpose of preserving any possible defense which the future might reveal, keeping alive actions to recover the amount paid for a period of six years. This would subject business men to limitless, contingent liabilities, and render the solvency or financial status of ^business institutions unascertainable. Furthermore, although we would not hold it indispensable in all cases, a penalty imposed for nonpayment is more readily construed as coercion in cases where the taxpayer has no opportunity to establish the illegality of the tax except in an action to recover back the money paid. Atchison, T. & S. F. R. Co. v. O’Connor, 223 U. S. 280, 32 Sup. Ct. 216. In the instant case the estate did urge the illegality of the tax before the county court, but the contention was not pressed by an appeal from the order of that court. This remedy was open and available to all who were interested in the determination of the tax. This remedy was accompanied by no greater penalty than that which follows a contest upon a promissory note. More than this, there is much reason to believe that the payment was made at the time not for the purpose of avoiding a penalty but to secure a discount. Taxes paid for such purpose are never held to be involuntary payments. Atchison, T. & S. F. R. Co. v. Humboldt, 87 Kan. 1, 123 Pac. 727; Louisville v. Becker, 139 Ky. 17, 129 S. W. 311; Lee v. Templeton, 13 Gray (79 Mass.) 476. Of such a payment, under an identical statute, the New York appellate court said: “Such payment is purely voluntary; the state neither invites nor compels it.” Socolow v. Murphy, 219 App. Div. 184, at p. 186, 219 N. Y. Supp. 78, 81. However, we do not rest our conclusion upon the premise that *247the purpose of the payment was to secure the discount. We have rather rested it upon the hypothesis that it was made to avoid the most drastic penalty that can be read out of the statute. That penalty is interest at the rate of six per centum per annum. A payment to avoid such a penalty does not constitute an involuntary payment, even though accompanied by a formal protest.
That the judgment or order of the county court determining the amount of the inheritance tax due and owing from the estate to the state is res adjudicata, conclusive between the parties, and immune from collateral attack, is freely conceded, unless such judgment is void. The plaintiffs contend that the order or judgment of the county court determining the amount of the inheritance tax is void because the court was without jurisdiction, because there was a denial of due process of law, and because the order is based upon an unconstitutional statute.
Sec. 72.12 of the Statutes confers upon county courts jurisdiction “to hear and determine all questions arising under the provisions of the inheritance tax laws and to do any act in relation thereto authorized by law to be done by a county court in other matters or proceedings coming within its jurisdiction.” The law confers jurisdiction to hear and determine all questions arising under its provisions. It is difficult to see how a broader jurisdiction could be conferred upon any court upon a given subject. It is all-inclusive. Jurisdiction has been defined as the “power to entertain the suit, consider the merits and render a binding decision thereon; and by merits we mean the various elements which enter into or qualify the plaintiff’s right to the relief sought.” General Inv. Co. v. New York Cent. R. Co. 271 U. S. 228, 46 Sup. Ct. 496.
In Tallman v. McCarty, 11 Wis. 401, at p. 406, it was said:
“No order which a court is empowered, under any circumstances in the course of a proceeding over which it has *248jurisdiction, to' make, can be treated as a nullity merely because it was made improvidently, or in a manner not warranted by law or the previous state of the case. The only question in such a case is, Had the court or tribunal the power, under any circumstances, to make the order or perform the act? If this be answered in the affirmative, then its decision upon those circumstances becomes final and conclusive until reversed by a direct proceeding for that purpose.”
To like effect: 14 Corp. Jur. 723-725, 729, 730; Harrigan v. Gilchrist, 121 Wis. 127, 99 N. W. 909; Comstock v. Boyle, 134 Wis. 613, 114 N. W. 1110; Will of Rice, 150 Wis. 401, 438-444, 136 N. W. 956, 137 N. W. 778; Fauntleroy v. Lum, 210 U. S. 230, 28 Sup. Ct. 641; Cooper v. Reynolds, 10 Wall. (77 U. S.) 308.
The statute vested the county court with power to determine the amount of the inheritance tax due from the estate. It therefore had jurisdiction over the subject matter. It is not contended that the court lacked personal jurisdiction necessary to enable it to determine such question. Possessing jurisdiction over the person and the subject matter, it proceeded to determine the amount of the tax. The estate was represented by counsel at such hearing. A question necessary to be determined was what gifts had been made in contemplation of death. It was conceded that the deceased had made substantial gifts prior to his death. Many of such gifts had been made within six years prior to his death. The inheritance tax counsel contended that under the statute such gifts should be conclusively presumed to have been made in contemplation of death. The attorneys for the estate offered to prove that they were not made in contemplation of death. If the statute were constitutional such evidence was immaterial. The court was called upon to decide whether the statute was constitutional. It was a judicial question of the highest order. It is not claimed that the attorneys for the estate were denied an opportunity to be *249heard upon this question. The court held the statute constitutional, which was equivalent to a holding that under the law of this state all gifts made within six years of the death of the grantor or donor should be included- in computing the inheritance tax due from the estate. Such ruling, as it subsequently transpired, was error, but it is inconceivable that it affected the jurisdiction of the court. True, it rendered any evidence upon the question whether such gifts were made in contemplation of death immaterial and irrelevant. As we understand counsel’s contention, they claim that at this point the estate was denied due process of law because it was not permitted to introduce evidence upon this question, and that because of such denial of due process of law the further proceedings of the court were void and without jurisdiction. In this connection counsel cite Windsor v. McVeigh, 93 U. S. 274; Hovey v. Elliott, 167 U. S. 409, 17 Sup. Ct. 841; People ex rel. A. V. S. B. & I. L. Co. v. Burke, 72 Colo. 486, 212 Pac. 837; Wanser v. Howland, 10 Wis. 8; Howe v. McGivern, 25 Wis. 525. We have examined those cases and they fall far short of supporting such contention. In fact, we should be very much surprised to find any reputable authority holding that such a situation amounted to a denial of due process of law. Courts frequently encounter just such situations. They must decide upon the admissibility of evidence. It not infrequently happens that plaintiff’s case depends entirely upon whether a certain class of evidence is admissible, a ruling upon which is practically decisive of the case. A ruling that the evidence is inadmissible does not constitute denial of due process of law where counsel is afforded an opportunity to be heard upon the question of its admissibility. The fact that in so ruling the court relies upon an unconstitutional -statute cannot affect the question. The ruling may be erroneous, but if the court has jurisdiction, to rule it has jurisdiction to err. The judgment fdllowing such a ruling is not a void judg*250ment which may be collaterally attacked. It is a judgment which’ may be reversed on appeal.
Neither are we impressed with the suggestion that evidence was necessary in order to give the court jurisdiction to impose an inheritance tax upon these gifts. The statute vested the court with jurisdiction to impose a tax upon all gifts made in contemplation of death. Having such jurisdiction, it was the judicial duty to ascertain what if any gifts had been made in contemplation of death. Evidence that there were such gifts was not necessary to jurisdiction. Rather jurisdiction was necessary to take such evidence. The court excluded such evidence because the law of the state was misconceived. Such ruling was within the jurisdiction of the court.
It is further contended that the judgment is based on an unconstitutional statute, that an unconstitutional statute is no statute and amounts to no more than if it had never been enacted, and that this renders the judgment void and subject to collateral attack. In the first place, the judgment is not based upon an unconstitutional statute. The judgment rests upon a statute which subjects gifts made in contemplation of death to an inheritance tax. This is not an unconstitutional statute. In determining what gifts were made in contemplation of death the court gave undue effect to an unconstitutional statute. This was error merely, and did not affect the jurisdiction of the court. But even though an unconstitutional statute furnished the only basis for the judgment of the court, the judgment did not constitute the subject of collateral attack. This is clearly, firmly, and definitely settled by the case of Arnold v. Booth, 14 Wis. 180.
If we are correct in our conclusion that the order of the county court determining the inheritance tax is a valid judgment of a court within its jurisdiction, a sanction of the present action constitutes an anomaly in our jurisprudence. *251It is a most fundamental rule that a judgment pronounced under such circumstances cannot be collaterally assailed. However, this form of action finds precedent in the decisions of this court. It was expressly sanctioned in Beals v. State, 139 Wis. 544, 121 N. W. 347, and permitted in Estate of Shepard, 184 Wis. 88, 197 N. W. 344. In Nunnemacher v. State, 129 Wis. 190, 108 N. W. 627, it was held that the determination of the inheritance tax was so far a judicial matter that the duty could properly be imposed upon a court. In Beals v. State, supra, it was said that the duties imposed upon the court were but steps in the enforcement of the tax law of the state rather than judgments in judicial controversies, and held that a suit would be entertained making a collateral attack upon such judgments. Since the decision of the Beals Case the almost uniform practice has been to secure relief from such judgments by appeal, as will appear from the citations in the earlier part of this opinion. In Estate of Shepard, supra, the court was urged to overrule the doctrine of the Beals Case. But the situation there presented induced the court to yield somewhat reluctant assent to the practice. Judgments of county courts determining inheritance taxes should be regarded as either fish or fowl. They are either judgments rendered in judicial controversies or they are not. The matter may be definitely determined here without affecting any rights, and we think it should be done not only in the interest of an orderly procedure but in fidelity to fixed principles of law. We are firmly convinced that judgments or orders of county courts determining inheritance taxes are judgments rendered in judicial proceedings and should not be the subject of collateral attack. We accordingly rule that the proper and exclusive way of reviewing such judgments is by appeal under statutes permitting appeals from judgments and orders of county courts.
*252From what has been said it follows that the demurrer to the answer should be overruled, and the allegations of the complaint held insufficient to state a cause of action.
By the Court. — Action dismissed.