delivered the opinion of the Court:
This bill attacks collaterally the validity of a decree of the Circuit Court of the United States. It alleges, for reasons hereafter to be noticed, that such decree is void, and therefore claims the right of those representing the makers of the trust deed, to redeem from it, just as if that decree had never been rendered. The general rule is, that where it is once made to appear that a court has jurisdiction, both of the subject matter and of the parties, the judgment or decree which it pronounces must be held conclusive and binding upon the parties thereto and their privies, notwithstanding the court may have proceeded irregularly, or erred in its application of the law in the ease before it. Cooley’s Const. Dim. (1st ed.) 408, et seq. There are cases which seem to be exceptional to this rule, but which, perhaps, are not, when rightly considered, where the court, although having jurisdiction of the person, and jurisdiction to adjudicate, when properly brought before it, upon the subject matter, renders a judgment not authorized by law in that class of cases, under any possible proofs,—as, for instance, in a common law case; a judgment without the verdict of a jury, there appearing to have been no waiver- by the parties in interest of the right to have a jury; a judgment punishing a party by imprisonment in the penitentiary, under an indictment for a riot, and a verdict of guilty thereunder. In such cases, it may, perhaps, in a technical sense, accurately enough, be said that the court has no jurisdiction of the subject matter of the particular judgment. But whether these cases fall strictly within the general rule, or form exceptions to it, can be of but little importance, in a practical point of view, so long as the grounds on which they rest are understood and kept in mind. They are not instances of mere misapplication of law to particular facts, or erroneous interpretation, of rules in particular cases, but they are attempts to exercise an authority which has no existence, in the particular case, *403under any possible state of proofs. See Windsor v. McVeigh, 93 U. S. 282; Lloyd v. Malone, 23 Ill. 43.
That there was jurisdiction in the United States Court to render the decree of foreclosure, the complainant being a citizen of Wisconsin, and the defendants citizens of this State, if there was jurisdiction of the defendants, is not denied; but it is contended, on behalf of plaintiffs in error, that there was not jurisdiction of the defendants, because, first, the summons that was issued was void, by reason of not being returnable at a day during the term at which it was issued; second, the guardian ad litem appointed for John Maloney, Jr., was clerk of the court, and therefore prohibited from practicing as a solicitor in chancery; third, William Maloney was insane at the time he was served with process and the decree was rendered; fourth, it does not appear that the summons was properly served.
The first and fourth objections are not based on any allegations in the bill, and should, on that ground, be disregarded. We will add, however, that, in our opinion, they would have been untenable if they had been alleged, because they are not sustained! by the record.
We are not aware of any statute, or ruling of any court, which requires that a guardian ad litem shall be a solicitor. Counsel for plaintiffs in error have called our attention to none, and in our opinion there are none. The acts of a guardian ad litem, after appointment, may be erroneous, but however much so, they can not be held to relate back, and divest the court of the personal jurisdiction which authorized it to make the appointment. After inquisition, and the appointment of a conservator for a lunatic, a party filing a bill to enforce the contracts of such lunatic should make the conservator a party. But until inquisition and the appointment of a conservator, it is competent to commence suit against the lunatic. The complainant is not bound to ascertain the mental capacity of *404the defendant, and have a conservator appointed, before he can bring suit. King v. Robinson, 33 Me. 114.
It is provided by section 6 of our Chancery Code, (Rev. Stat. 1874, p. 199,) “that in any cause in equity it shall be lawful for the court in which the cause is pending, to appoint a guardian ad litem to any * * * insane defendant in such cause,” etc. But this is not made jurisdictional, and, obviously, it can have no application where a conservator has been appointed, and is acting, or where the complainant had no knowledge of the' insanity. The record here shows that there was no inquisition and no appointment of a conservator until after the summons was served, and there is neither averment nor proof that Dewey had any knowledge of "William’s insanity before the decree was rendered.
It has been held, that where an insane person has been properly before the court, “acts done by matter of record, as, fines, recoveries, judgments, statutes, recognizances, etc., shall hind as well the idiot as he who becomes non compos mentis.” Beverly’s case, 4 Co. 123; Mansfield’s case, 12 id. 124; Fonbl. Eq. b. 1, c. 2, sec. 2, note k. See King v. Robinson, supra, at page 123.
It is said that judgments against lunatics are neither void nor voidable, (Freeman on Judgments, sec. 123,) and that the proper remedy for a lunatic is to apply to chancery to restrain the proceedings, and to compel the plaintiff to go there for justice. (Ibid.) So, also, the same author, in a note to Allison v. Taylor et al. 32 Am. Dec. 70, in speaking of a judgment against a lunatic, says: “Unless set aside in chancery, or by some other appropriate remedy, a judgment against a lunatic is of unquestionable validity. Lamprey v. Nudd, 9 Fost. 299; Wood v. Bayard, 63 Pa. St. 320; Foster v. Jones, 23 Ga. 168; Sacramento Savings Bank v. Spencer, 53 Cal. 737; Stigers v. Brent, 50 Md. 214; Johnson v. Pomeroy, 31 Ohio St. 247. If an attempt were made to vacate or enjoin such judgment in chancery, doubtless, the mere insanity of the judg*405ment defendant would not be a sure guaranty of success. It would require the aid of other facts, from which the conclusion must follow that the judgment is inequitable and can not be executed without injustice.” But since, in this case, it is the decree of a court of chancery, and not the judgment of a court of law, that is affected by the insanity, the requisite equitable jurisdiction is in the same court, and that court has all the jurisdiction that any court can have to relieve against any harm resulting from the decree. The decisions in this State and in other States are numerous to the point, and hold that there is no authority in the courts of one State to review, or to revise and supplement and correct, the decrees of courts of other States or of the United States. Hanna et al. v. Read et al. 102 Ill. 596; Wetherbee v. Fitch, 117 id. 67; Ritchie v. Pease, 114 id. 353; Sproehnle v. Dietrich, 110 id. 202; Logan v. Lucas, 59 id. 238; Munson v. Harroun, 34 id. 422; In re Salisbury, 16 id. 351. Necessarily, therefore, if William Maloney was inj uriously affected by the decree, those representing him should have applied to the court rendering the decree, to open it, and let them in to be heard.
The objection is urged, that the decree rendered is erroneous, because it directs a sale without redemption. But that error does not divest the United States Circuit Court of jurisdiction of the case. The remedy is, to apply to that court. What effect that error might have were this a suit at law, and the claim were made that the deed from the master was void because of such error, we will not undertake to decide. But this is a proceeding in equity, to redeem from a deed of trust that a Federal court has foreclosed. Whether the decree is erroneous in respect of the order of sale, or not, can not affect the jurisdiction of that court to render final decree. If this decree should be reversed on review or error, that court would still have the exclusive jurisdiction to render final decree in the case, and necessarily, therefore, some other court could not have jurisdiction to render a decree that redemption under the *406deed of trust be allowed. The right of redemption is involved in the question of foreclosure. No decree can be rendered in such a case without passing upon it, and the court first obtaining jurisdiction to pass upon it must retain that jurisdiction to the end. Ex parte Jenkins, 2 Wall., Jr., C. C. 521; Wallace v. McConnell, 13 Pet. 151.
Other objections urged against the decree involve merely questions of erroneous rulings, unaffected by the question of jurisdiction, and can not therefore be considered in this collateral way.
The decree is affirmed.
Decree affirmed.