As to the conduct of plaintiff Rue Fern McFarland, it is true that she joined with her brother in instituting this suit. It is also true that no offer to do equity is made in plaintiffs' complaint herein and the cause of suit stated therein makes no references to the Oklahoma property, but as to Mrs. McFarland we think her course ill-advised, but not inequitable, for the reason that she had no control over the Oklahoma property, the retention of the title to which by her brother being of the essence of his inequitable conduct. It is urged that the maxims to the effect that he who seeks equity must do equity and that he who comes into equity must come with clean hands are not applicable unless pleaded by the party who seeks to invoke them. With this, we do not concur. Ward v. Lovell, 21 Tenn. App. 560, 113 S.W.2d 759; Duggan v. Platz, 263 N.Y. 505, 189 N.E. 566; East Tennessee and Western North Carolina Ry. Co. v. Robinson, 19 Tenn. App. 265, 86 S.W.2d 433; Bell Howell Co. v. Bliss, 262 F. 131; Brownley v. Peyser, 69 App. D.C. 56, 98 F.2d 337, 341; Gest v. Gest, 117 Conn. 289, 167 A. 909, 913, and cases there cited. In Carmichael v. Carmichael, 106 Or. 198, 209, 211 P. 916, it is said that —

But the fact that the Illinois conservator, who has undertaken to prosecute this appeal in behalf of his sister, the defendant, has not been appointed either general guardian or guardian ad litem by any Nevada court, is not a fatal jurisdictional defect requiring dismissal of the appeal. Yarhola v. Duling, 86 Okla. 171, 207 P. 293; In re Prouty's Estate, 101 Vt. 496, 144 A. 691; St. Louis, I.M. S.R. Co. v. Haist, 71 Ark. 258, 72 S.W. 893, 100 Am. St. Rep. 65; Hill v. Reed, 23 Okla. 616, 103 P. 855; Ward v. Lovell, 21 Tenn. App. 560, 113 S.W.2d 759; Home Life Ins. Co. v. Cohen, 278 Mich. 169, 270 N.W. 256; Kearney v. Doyle, 22 Mich. 294; Carlton v. Miller, 2 Tex. Civ. App. 619, 21 S.W. 697; Bancroft, Code Pr. and Rem., vol. 6, p. 6357, sec. 4849, notes 20, 2; Bancroft, Code Pl., Pr. and Rem., Ten Year Supp., vol. 4, p. 3520, sec. 4849; 4 C.J.S., Appeal and Error, sec. 1353, p. 1943, sec. 1365, page 1977, note 75; 10 Stand. Encyc. of Proc. 726, note 91; 10 Encyc. of Pl. and Pr. 1231, note 3. Respondent points out that Mr. Cornbleet did not at any time apply to a Nevada court for appointment as general guardian of Matilda Baker, and suggests that if he had done so such court might well have granted his petition.

Even if we were to disregard the District Attorney General's motion, the question of subject matter jurisdiction is one that the trial court could have and should have raised on its own motion. Scales v. Winston, 760 S.W.2d 952, 953 (Tenn.Ct.App. 1988); Tritschler v. Cartwright, 46 Tenn. App. 662, 665, 333 S.W.2d 6, 8 (1959); Ward v. Lovell, 21 Tenn. App. 560, 563, 113 S.W.2d 759, 760 (1938). Accordingly, for the purpose of this appeal, we will consider the question of subject matter jurisdiction as if the trial court had raised it on its own motion.

Any order entered by a court without subject matter jurisdiction is a nullity and is therefore unenforceable. See Scales, 760 S.W.2d at 953; Ward v. Lovell, 113 S.W.2d 759, 760 (Tenn.Ct.App. 1937). We note the case of Kilby v. Kilby, No. 03A019712-CH00549, 1999 WL 76065, at *1 (Tenn.Ct.App. Jan. 28, 1999).

SeeState ex rel. Dep't of Social Servs., 736 S.W.2d 84, 85 n. 2 (Tenn 1987); Scales v. Winston, 760 S.W.2d 952, 953 (Tenn.App. 1988) Any order entered by a court without subject matter jurisdiction is a nullity and is therefore unenforceable. See Scales, 760 S.W.2d at 953; Ward v. Lovell, 113 S.W.2d 759, 760 (Tenn. App 1937). In the instant case, the parties do not dispute that the trial court had subject matter jurisdiction at the time of its original order requiring Mr. Day to pay child support.

" In Scales v. Winston, 760 S.W.2d 952, 953 (Tenn. App. 1988), the Court of Appeals observed: "It is the duty of any court to determine the question of its jurisdiction on its own motion if the issue is not raised by either of the parties, inasmuch as any judgment rendered without jurisdiction is a nullity. Ward v. Lovell, 21 Tenn. App. 560, 113 S.W.2d 759 (1937)." In County of Shelby v. City of Memphis, 211 Tenn. 410, 411, 365 S.W.2d 291, 292 (1963), our Supreme Court sua sponte reversed the judgment of the trial court and dismissed the appeal because the Court found that the trial court did not have subject-matter jurisdiction.

It is the duty of any court to determine the question of its jurisdiction on its own motion if the issue is not raised by either of the parties, inasmuch as any judgment rendered without jurisdiction is a nullity. Ward v. Lovell, 21 Tenn. App. 560, 113 S.W.2d 759 (1937). Although phrased somewhat loosely, we will treat the defendant's motion to dismiss in the trial court as one challenging the jurisdiction of that court.