Chief Justice JEFFERSON delivered the opinion of the Court.

When the State seeks to sever permanently the relationship between a parent and a child, it must first observe fundamentally fair procedures.1 The most basic of these is notice. If the State cannot deliver notice in person, it may try other means that will likely reach the parent.2 We consider today whether serving the parent in a newspaper advertisement, "a poor and sometimes a hopeless substitute for actual service,"3 is constitutionally acceptable when the State knew the mother's identity, was in regular contact with her, and had at least one in-person meeting with her after it sued to terminate the legal rights to her children. We conclude that the substituted service was poor, hopeless, and unjustifiable under these circumstances.

But that does not end our inquiry. A parental rights termination proceeding encumbers a value "far more precious than any property right"4 and is consequently governed by special rules.5 We are faced not with the ordinary dispute about how to allocate money in a contract or tort action. We must decide how to reconcile a parent's desire to raise her child with the State's responsibility to promote the child's best interest. The Legislature and our courts have labored to ensure that proceedings to terminate a parent's legal relationship to her child are handled efficiently. To promote permanency in child rearing at the earliest stage possible, the Legislature has enacted a strict six-month deadline to challenge a termination judgment following citation by publication.6 For reasons we explain below, that strict time limit cannot foreclose a challenge when the parent has no constitutionally adequate notice of the proceeding. On the other hand, because a parent must remain vigilant with respect to her child's welfare, and because courts must always consider the child's best interest, a parent who learns about a judgment terminating the bonds to her child must act diligently to restore that right.

We reverse the court of appeals' judgment affirming the termination of parental rights. We remand the case to the trial court to determine whether the mother unreasonably failed to act after knowing that a final judgment had taken away her children, and if so, whether granting relief would impair another person's substantial interest in reliance on that judgment.

I. Background

Several months after removing L.R.'s four children from her home and becoming their temporary managing conservator, the Department of Family Protective Services petitioned the trial court to terminate L.R.'s parental rights. After an unsuccessful attempt at personal service, the Department decided to serve L.R. by publication. Felicia Chidozie, the caseworker, prepared an affidavit summarizing her attempts to locate L.R. Although she had L.R.'s phone number, Chidozie said that L.R. told her that she was in the process of moving and did not have a permanent address. Chidozie ran a background check through IMPACT, which confirmed the address Chidozie already possessed. Chidozie also checked a website, www.anywho.com, and found no listing. Chidozie's call to the Texas Vine System was fruitless, and the Salvation Army refused on confidentiality grounds to answer her query. Chidozie faxed TXU Electric, Missing Person's Clearinghouse, Voter Registration, and Adult Probation, but received no responses in the two days between sending the faxes and filing her affidavit stating that L.R. could not be located. Finally, Chidozie called the "motor vehicle Tax Roles" but was told that it could locate information only from property or motor vehicle numbers. Based on this affidavit, the trial court authorized service by publication.

The Department published the citation,7 and the trial court conducted a final hearing. L.R. did not appear. The hearing transcript spans twelve double-spaced pages. Two witnesses testified: Chidozie and Erica Finley, the children's guardian and "aunt."8 Chidozie testified that she searched diligently for L.R. and signed an affidavit chronicling her efforts. She stated that L.R. had visited the children at the Department's offices a month before the termination hearing.9 Chidozie said that L.R. gave her a phone number but would not provide an address. Chidozie contacted L.R. at that phone number and gave her information about court hearings. Chidozie testified that L.R. attended the hearings, but was tardy each time. Chidozie said L.R. had knowingly placed or knowingly allowed the children to remain in conditions or surroundings that endangered their physical or emotional well-being. According to Chidozie, the children were physically abused, and L.R. tested positive for methamphetamine when she gave birth to her youngest child. Chidozie testified that the children were doing well in Finley's home and that termination would be in their best interest. She stated that the Department's plan was to be named the permanent managing conservator and for the children to be adopted.

Finley testified that the children had been living with her for approximately six months, that they were happy, and that she planned to adopt them. Joe Rosenfield, the children's guardian ad litem, stated that Finley wanted the children, and they were doing well under her care. He opined that termination would be in the children's best interest.

Brenda Hull Thompson, who appeared as "publication attorney,"10 stated that L.R. was served by publication and that publication was "ripe" on October 15, 2007. Thompson apparently never met with L.R. and learned for the first time at the hearing that L.R. had personally visited the children at the Department's offices. Thompson made no other statements about L.R., nor did she opine that termination would be in the children's best interest. The trial court terminated L.R.'s parental rights as well as those of the putative fathers, and it appointed the Department permanent managing conservator.

L.R. moved for a new trial within two years of the judgment. See TEX.R. CIV. P. 329(a) (authorizing trial court to grant motion for new trial filed within two years of judgment, if judgment rendered on service by publication and defendant did not appear in person or by attorney of her own selection). She complained that service by publication was obtained by fraud and was invalid because, among other things, she had been in regular, personal contact with Chidozie and visited the children at the Department offices during the time the Department was attempting to serve her. L.R. denied ever telling Chidozie that she did not have an address at which she could be served; instead, she asserted that she told Chidozie she did not have an address separate from her mother's, which Chidozie already had. L.R. also challenged Chidozie's affidavit.

The Department argued that L.R.'s motion was untimely because it was filed beyond Rule 329's two-year deadline.11 Chidozie disputed L.R.'s characterization of their conversation about her address, but Chidozie admitted that she met with L.R. in the Department's offices for a prescheduled meeting in August 2007. The Department did not cite the Family Code's six-month deadline for attacking termination decrees.12 The trial court denied the motion, and L.R. appealed.

In her appellate brief, L.R. included a footnote citing Family Code section 161.211 but argued that the matter was an affirmative defense that the Department waived by failing to raise it in the trial court, citing In re Bullock, 146 S.W.3d 783, 790-91 (Tex.App. — Beaumont 2004, no pet.). The Department's brief cited the same case and agreed that "[t]he six-month limitation in section 161.211 is an affirmative defense, which is waived if not presented to the trial court.... If the State's argument regarding the timeliness of the motion was not sufficient to invoke the six-month limitation in section 161.211, appellant's November 16, 2009 motion for new trial was timely under rule 329(a)...."

Three months after briefing had been completed, the Department filed an amended brief, now arguing that section 161.211 absolutely barred challenges made more than six months after the order was signed, and that the court of appeals should not reach the merits because L.R.'s motion was untimely.

A divided court of appeals agreed. 335 S.W.3d 816. The court held that section 161.211's six-month deadline was dispositive: "The mandatory language of family code section 161.211 leaves no room for a construction other than a requirement that any collateral or direct attack on the termination of parental rights, including a motion for new trial, be filed no more than six months after the termination order is signed." Id. at 820. Because L.R.'s challenge was not filed within that period, it was barred. The court of appeals held that L.R. had not raised a constitutional challenge and thus had not preserved or presented the issue for review. Id. at 823.

The dissent concluded that the six-month deadline applied only to people who were validly served by publication. Id. at 827 (Murphy, J., dissenting). Because service on L.R. was invalid, the deadline was inapplicable:

Id. at 829. The dissent determined that L.R. was never validly served by publication because the Department had L.R.'s working phone number and a contact address, the caseworker met with L.R. during the time service by publication was being pursued, the Department knew the whereabouts of at least one relative, and Chidozie's affidavit was inconsistent with her live testimony. Id. at 832.

We granted L.R.'s petition for review.13 55 Tex.Sup.Ct.J. 145 (Dec. 16, 2011).

II. Citation by Publication

A. History

Citation by publication is a form of substituted service that, through a small notice published in the classified section of a local newspaper, is meant to apprise a defendant that her rights are at stake. Courts have accepted this method for more than a century. See, e.g., Pennoyer v. Neff, 95 U.S. 714, 727, 24 L.Ed. 565 (1877); Harris v. Daugherty, 74 Tex. 1, 11 S.W. 921, 922 (1889). Sixty years ago, however, the Supreme Court squarely addressed the practice's due process implications. See Mullane v. Cent. Hanover Bank & Trust Co., 339 U.S. 306, 70 S.Ct. 652, 94 L.Ed. 865 (1950). Mullane remains the seminal case involving notice by publication, and it explains how to evaluate the adequacy of notice. See 4A CHARLES ALAN WRIGHT & ARTHUR R. MILLER, FEDERAL PRACTICE AND PROCEDURE § 1074, at 368 (3d ed.2002) (noting that Mullane "is recognized as the keystone of the modern philosophy regarding the due process aspects of a notice requirement and the importance of the case should not be underestimated"). We measure the constitutionality of notice using Mullane's analytical framework, rather than Mathews v. Eldridge's balancing test.14 Dusenbery v. United States, 534 U.S. 161, 167-68, 122 S.Ct. 694, 151 L.Ed.2d 597 (2002).

Mullane involved a common trust fund, a mechanism for pooling small trusts to simplify their administration. Mullane, 339 U.S. at 307-08, 70 S.Ct. 652. Under New York law, once such a fund had been established, its beneficiaries could be served by publication for four successive weeks. Id. at 309-10, 70 S.Ct. 652. Central Hanover established a common trust fund and petitioned the court for settlement of its first account as common trustee. Id. at 309, 70 S.Ct. 652. Central Hanover provided publication notice to beneficiaries. Id. A court-appointed attorney retained to represent the beneficiaries complained that notice by publication was constitutionally inadequate. Id. at 311, 70 S.Ct. 652.

The Supreme Court agreed. The Court observed that "[m]any controversies have raged about the cryptic and abstract words of the Due Process Clause but there can be no doubt that at a minimum they require that deprivation of life, liberty or property by adjudication be preceded by notice and opportunity for hearing appropriate to the nature of the case." Id. at 313, 70 S.Ct. 652. The Court noted that personal service was the classic form of notice "always adequate in any type of proceeding." Id. at 313-14, 70 S.Ct. 652. But personal service is not always necessary, and "[a] construction of the Due Process Clause which would place impossible or impractical obstacles in the way could not be justified." Id. But "when notice is a person's due, process which is a mere gesture is not due process." Id. at 315, 70 S.Ct. 652. The Court then outlined some of the problems with publication notice:

Id. For missing or unknown persons, service by this "indirect and even ... probably futile" means did not raise due process concerns. Id. at 317, 70 S.Ct. 652. But as to a known beneficiary with a known address, the Court concluded, notice by publication was constitutionally defective because it was not "reasonably calculated, under all the circumstances, to apprise interested parties of the pendency of the action and afford them an opportunity to present their objections." Id. at 314, 319, 70 S.Ct. 652.

The Court revisited Mullane thirty-three years later in Mennonite Board of Missions v. Adams, 462 U.S. 791, 103 S.Ct. 2706, 77 L.Ed.2d 180 (1983). There, a landowner signed a mortgage in favor of the Mennonite Board of Missions. Mennonite, 462 U.S. at 792, 103 S.Ct. 2706. After the landowner failed to pay property taxes, the county began proceedings to sell the property. Id. at 794, 103 S.Ct. 2706. Indiana law required that notice be posted at the county courthouse and published for three consecutive weeks. Id. at 793, 103 S.Ct. 2706. Afterwards, the county could sell the property to the highest bidder. Id. After the auction, a two-year redemption period commenced during which those with an interest in the property could pay the delinquency. Id. Failing that, the purchaser acquired the deed. Id. at 794, 103 S.Ct. 2706.

The county published notice and auctioned the property. Id. Adams, as the high bidder, sued to quiet title to the property. Id. at 794-95, 103 S.Ct. 2706. Mennonite did not learn of the tax sale until after the redemption period had expired. Id. at 794, 103 S.Ct. 2706. Mennonite argued that publication notice of the tax sale was constitutionally inadequate. Id. at 795, 103 S.Ct. 2706. The Indiana courts rejected this argument, but the Supreme Court held that "unless the mortgagee is not reasonably identifiable, constructive notice [by publication] alone does not satisfy the mandate of Mullane." Id. at 798, 103 S.Ct. 2706. The Court observed that Mennonite's identity was known, and it assumed that Mennonite's address could have been ascertained by reasonably diligent efforts. Id. at 798 n. 4, 103 S.Ct. 2706. The Court held that "[n]otice by mail or other means as certain to ensure actual notice is a minimum constitutional precondition to a proceeding which will adversely affect the liberty or property interests of any party, whether unlettered or well versed in commercial practice, if its name and address are reasonably ascertainable." Id. at 800, 103 S.Ct. 2706. The Court reversed the Indiana Court of Appeals' judgment and held that publication notice failed to provide Mennonite with due process.

In a similar vein, the Supreme Court has rejected publication notice to known creditors or those whose identities are "reasonably ascertainable"15 and to known landowners in condemnation proceedings.16 The Court has also held that tenants were denied due process when served only by posted notice in an eviction proceeding,17 and that class members whose names and addresses could be ascertained through reasonable effort cannot be served by publication.18

From these decisions, we can distill a common principle: when a defendant's identity is known, service by publication is generally inadequate. See, e.g., 1 RESTATEMENT (SECOND) OF JUDGMENTS § 2, reporter's note cmt. a (1982) ("Some courts still do not seem to have appreciated the thrust of Mullane. ... The critical distinction is between notice to known claimants and notice to persons unknown. Notice by publication meets the requirement of adequate notice as to the latter but not as to the former.").

Notice by publication, constitutionally suspect in 1950, is even more vulnerable today, given the precipitous decline in newspaper readership. See Jennifer Lee Case, Note, Extra! Read All About It: Why Notice by Newspaper Publication Fails to Meet Mullane's Desire-to-Inform Standard and How Modern Technology Provides a Viable Alternative, 45 GA. L.REV. 1095, 1097 (2011) (observing that, when Mullane was decided, over 80% of American adults read a weekday newspaper; today that number is 50%). One thing is clear: service by publication should be a last resort, not an expedient replacement for personal service.19 Because "[n]otice by publication is a poor and sometimes a hopeless substitute for actual service of notice[,] ... [i]ts justification is difficult at best." City of New York v. N.Y., New Haven & Hartford R.R. Co., 344 U.S. 293, 296, 73 S.Ct. 299, 97 L.Ed. 333 (1953); see also Walker v. City of Hutchinson, 352 U.S. 112, 117, 77 S.Ct. 200, 1 L.Ed.2d 178 (1956) ("In too many instances notice by publication is no notice at all.").

B. A State law time limit is unenforceable when it violates due process.

Mullane's due process requirements displace state statutes that restrict the time for challenging a judgment. In Tulsa Professional Collection Services, Inc. v. Pope, 485 U.S. 478, 108 S.Ct. 1340, 99 L.Ed.2d 565 (1988), the Supreme Court examined whether notice by publication deprived a creditor of due process. H. Everett Pope, Jr., was hospitalized at St. John Medical Center, where he later died. Tulsa Prof'l, 485 U.S. at 482, 108 S.Ct. 1340. His wife initiated probate proceedings and, pursuant to Oklahoma law, published notice to creditors. Id. At that time, Oklahoma's nonclaim statute20 required creditors to file claims against an estate within two months, otherwise their claims would be "barred forever." Id. at 481, 108 S.Ct. 1340. The statute required only service by publication. Id. Tulsa Professional Collection Services, the hospital's assignee, filed its claim after the two-month deadline. Id. at 482, 108 S.Ct. 1340. The trial court denied the claim, the Oklahoma Court of Appeals affirmed, rejecting Tulsa's argument that notice by publication violated due process, and the Oklahoma Supreme Court agreed. In re Estate of Pope, 733 P.2d 396, 398 (Okla.1986).

The U.S. Supreme Court reversed. Tulsa Prof'l, 485 U.S. at 491, 108 S.Ct. 1340. The Court noted that the State had a legitimate interest in resolving probate proceedings expediently, and it observed that "the almost uniform practice is to establish such short deadlines, and to provide only publication notice." Id. at 489, 108 S.Ct. 1340. Nonetheless, the Court held that service by publication was unconstitutional as to known creditors or those whose identities were "reasonably ascertainable," concluding that another form of service that would provide "actual notice to [such] creditors is not so cumbersome as to unduly hinder the dispatch with which probate proceedings are conducted." Id. at 490, 108 S.Ct. 1340. The Court remanded for the trial court to determine whether Tulsa's identity as a creditor was known or reasonably ascertainable. If it was, "then termination of appellant's claim without actual notice violated due process," regardless of the statutory two-month deadline for filing claims. Id.; see also Greene v. Lindsey, 456 U.S. 444, 456, 102 S.Ct. 1874, 72 L.Ed.2d 249 (1982) (holding that tenants were denied due process when served only by posting, regardless of the fact that tenants did not file their challenge until after default judgments had been entered against them and their time for appeal had lapsed); Schroeder v. New York, 371 U.S. 208, 211, 83 S.Ct. 279, 9 L.Ed.2d 255 (1962) (holding that publication notice "did not measure up to the quality of notice" demanded by the Due Process Clause even though challenge not filed within statutory three year limitations period); Walker v. City of Hutchinson, 352 U.S. 112, 116, 77 S.Ct. 200, 1 L.Ed.2d 178 (1956) (holding that publication notice deprived landowner of due process even though collateral attack filed after deadline for appeal had passed).

Most state courts that have considered the issue have reached a similar conclusion: due process prevails over a state law time limit, even one imposed on challenges to termination of parental rights or adoptions.21

C. Citation by publication deprived L.R. of due process.

With these principles in mind, we examine whether citation by publication was proper in this case. Parental rights are "far more precious than any property right," and when the State initiates a termination proceeding, "it seeks not merely to infringe that fundamental liberty interest, but to end it." Santosky v. Kramer, 455 U.S. 745, 758-59, 102 S.Ct. 1388, 71 L.Ed.2d 599 (1982). We carefully scrutinize termination proceedings, and we strictly construe involuntary termination statutes in the parent's favor. Holick v. Smith, 685 S.W.2d 18, 20 (Tex.1985); cf. United States v. Kiriaze, 172 F.2d 1000, 1002 (5th Cir.1949) ("When, then, the United States, as here, seeks not by actual notice to the citizen but by substituted service by publication to deprive him of this priceless right [of citizenship], it must strictly comply with the statute authorizing such service.").

Personal jurisdiction, a vital component of a valid judgment, is dependent "upon citation issued and served in a manner provided for by law." Wilson v. Dunn, 800 S.W.2d 833, 836 (Tex.1990). If service is invalid, it is "of no effect" and cannot establish the trial court's jurisdiction over a party. Uvalde Country Club v. Martin Linen Supply Co., 690 S.W.2d 884, 885 (Tex.1985) (per curiam). When judgment is rendered on service of process by publication, a party has two years to move for a new trial, which the trial court may grant for "good cause." TEX.R. CIV. P. 329(a). But if service was invalid, a party is entitled to a new trial without showing good cause.22

The Family Code permits service by publication for individuals who cannot be served personally or through the mail, or if a person's name is unknown. TEX. FAM.CODE § 102.010(a). Citation by publication is served "as in other civil cases," id., and the trial court must "inquire into the sufficiency of the diligence exercised in attempting to ascertain the residence or whereabouts of the defendant ... before granting any judgment on such service." TEX.R. CIV. P. 109; see also TEX. FAM.CODE § 161.107(b) ("If a parent of the child has not been personally served in a suit in which the Department of Family and Protective Services seeks termination, the department must make a diligent effort to locate that parent."). A lack of diligence makes service by publication ineffective. Anderson v. Collum, 514 S.W.2d 230, 231 (Tex.1974).

We have said that "[i]f personal service can be effected by the exercise of reasonable diligence, substituted service is not to be resorted to." Sgitcovich v. Sgitcovich, 150 Tex. 398, 241 S.W.2d 142, 147 (1951) (quoting 42 AM. JUR. § 65, p. 54). Yet we have never explained what a diligent search involves. Other courts have. The Illinois Supreme Court recently held that "because service by publication is meant as a last resort of serving summons, it should be used only after a genuine diligent inquiry to locate the individual has been completed. Put simply, relying on a computerized database search of a parent's name while ignoring, or otherwise not investigating, other potentially useful information does not constitute a diligent inquiry" under Illinois law. In re Dar. C., 354 Ill.Dec. 304, 957 N.E.2d 898, 912 (Ill.2011) (holding that service by publication was defective, thus depriving trial court of jurisdiction and rendering its judgment void); see also id. at 921-22 (Burke, J., concurring) (noting that when state's attorney is in actual contact with parent several months before default judgment terminating parental rights, previously issued publication notice is insufficient).

The Iowa Supreme Court reached a similar conclusion, where an investigator "failed to exhaust all reasonable means to discover [the father's] whereabouts to ensure that he did receive notice of the termination proceeding." In the Interest of S.P., 672 N.W.2d 842, 848 (Iowa 2003). The father's identity was known, although his address was not. The court held that in determining whether a search is diligent, courts must examine the methods employed to locate the missing person to see if they were made through channels expected to supply the missing identity. Id. at 846. Although the court held that a party need not use "all possible or conceivable means of discovery,", a reasonable search "is an inquiry that a reasonable person would make, and it must extend to places where information is likely to be obtained and to persons who, in the ordinary course of events, would be likely to have information of the person or entity sought." Id. Thus, although an investigator from the county attorney's office checked with various governmental agencies, private databases, and city directories, and visited addresses where he thought the father might live, he failed to include "the obvious inquiries a reasonable person would make under the circumstances." Id. at 848. He did not talk to the children, their caretaker, or their mother. Nor did he mail notice to the various addresses he had to find a forwarding address. Because the efforts fell short of a reasonably diligent search, the father was denied an opportunity to be heard, and the termination judgment was vacated. Id.

The Nebraska Supreme Court reached the same result. In re Interest of A.W., 224 Neb. 764, 401 N.W.2d 477, 478-80 (1987). Thus, where a mother's identity was known, service by publication was not justified even though the mother had said that she was going "underground for a while" because she had written a bad check and the police were looking for her. Id. at 479. The department of protective services did not contact her mother, who probably had an address for her. Id. Because the search was "less than reasonably diligent," the mother was improperly deprived of an opportunity to be heard. Id. at 480. The court vacated the termination order and remanded the case for further proceedings. Id.

Similarly, a Georgia appellate court recently concluded that service by publication was improper in a parental rights termination case. See Taylor v. Padgett, 300 Ga.App. 314, 684 S.E.2d 434, 438 (2009). Even though the mother said she was living in a truck, the paternal grandparents had her phone number and could communicate with her. Id. at 435-37. Additionally, the mother had tried to see the children less than two weeks before the hearing. Finally, her relatives could have been contacted. Id. at 437. "Despite the existence of these reasonably available channels of information, the [grandparents] pursued none of them prior to obtaining an order for service by publication upon [the mother].... Accordingly, the record fails to support the juvenile court's determination that service by publication was proper." Id.

We agree with the principles stated in these cases. A diligent search must include inquiries that someone who really wants to find the defendant would make,23 and diligence is measured not by the quantity of the search but by its quality. Even disregarding the factual dispute about what L.R. told Chidozie about her address, the uncontroverted evidence here establishes a lack of diligence. Chidozie neglected "obvious inquiries" a prudent investigator would have made. In the Interest of S.P., 672 N.W.2d at 848. She did not contact L.R.'s mother, nor she did attempt service by mail in an effort to obtain a forwarding address. She did not pursue other forms of substituted service that would have been more likely to reach L.R., such as leaving a copy with L.R.'s mother. See TEX.R. CIV. P. 106(b)(1); see also McDonald v. Mabee, 243 U.S. 90, 92, 37 S.Ct. 343, 61 L.Ed. 608 (1917) ("To dispense with personal service the substitute that is most likely to reach the defendant is the least that ought to be required if substantial justice is to be done."). Even if L.R.'s address was not "reasonably ascertainable," an address was unnecessary for personal service on L.R. because she visited the Department's offices during the relevant time period. When a known parent has not left the jurisdiction, when she has attended at least two court hearings and has come to the Department offices for a prescheduled, hour-long meeting with her children during the very period service was being attempted, and when the Department can reach her by telephone and can communicate with her family members, service by publication cannot provide the kind of process she is due. Sending a few faxes, checking websites, and making three phone calls — none of which were to L.R. or her family members — is not the type of diligent inquiry required before the Department may dispense with actual service in a case like this. Mullane authorized service by publication when "it is not reasonably possible or practicable to give more adequate warning." Mullane, 339 U.S. at 317, 70 S.Ct. 652.24 Here, it was both possible and practicable to more adequately warn L.R. of the impending termination of her parental rights, and notice by publication was therefore constitutionally inadequate. Jones v. Flowers, 547 U.S. 220, 237, 126 S.Ct. 1708, 164 L.Ed.2d 415 (2006).

D. Because service was invalid, Family Code section 161.211 does not bar L.R.'s claim.

We must next decide the effect of the failure to provide adequate notice. Family Code section 161.211 provides that "the validity of an order terminating the parental rights of a person who is served by citation by publication is not subject to collateral or direct attack after the sixth month after the date the order was signed." TEX. FAM.CODE § 161.211(b). L.R. contends — as did the dissent below — that this bar applies only to parents for whom service by publication is valid. Failing that, L.R. argues that the statute is unconstitutional as applied to her.25

Whether we conclude that the statute applies only if service was valid or that the statute is unconstitutional as applied to L.R., the reasoning and result are the same in this case. A complete failure of service deprives a litigant of due process and a trial court of personal jurisdiction; the resulting judgment is void and may be challenged at any time. See Tulsa Prof'l, 485 U.S. at 491, 108 S.Ct. 1340 (holding that due process violation made judgment vulnerable to attack even though challenge filed beyond statutory two-month deadline); Peralta v. Heights Med. Ctr. Inc., 485 U.S. 80, 86, 108 S.Ct. 896, 99 L.Ed.2d 75 (1988) (concluding that Texas bill-of-review requirements must yield to constitutional demands of due process); Browning v. Prostok, 165 S.W.3d 336, 346 (Tex. 2005) (recognizing that judgment void for lack of personal jurisdiction could be collaterally attacked); see also supra note 21. McEwen v. Harrison, 162 Tex. 125, 345 S.W.2d 706, 711 (1961), has conflicting language, but its pronouncement on that subject must yield to contrary precedent from the U.S. Supreme Court. Accordingly, the statute cannot place a temporal limit on a challenge to a void judgment filed by a defendant who did not receive the type of notice to which she was constitutionally entitled.26 Despite the Legislature's intent to expedite termination proceedings, it cannot do so at the expense of a parent's constitutional right to notice. Cf. In the Interest of M.N., 262 S.W.3d 799, 803 (Tex. 2008) (noting that Family Code did not indicate legislative intent to unfairly or unreasonably preclude parents from appealing final orders).

We appreciate the policy concerns the Department identifies. It, the parent, and the child share an interest in a quick and final decision. In the Interest of M.S., 115 S.W.3d 534, 548 (Tex.2003). But finality cannot trump a parent's constitutional right to be heard. Stanley v. Illinois, 405 U.S. 645, 646, 92 S.Ct. 1208, 31 L.Ed.2d 551 (1972) (noting that "the Constitution recognizes higher values than speed and efficiency"). We have twice held that Family Code provisions that expedite termination proceedings must yield to due process. See In the Interest of B.G., 317 S.W.3d 250, 258 (Tex.2010) (holding that failure to file requisite statement of appellate points could not, consistent with due process, form a basis for denying parent an appellate record and that Family Code section 263.405 was unconstitutional as applied to parent); In the Interest of J.O.A., 283 S.W.3d 336, 339, 347 (Tex.2009) (holding that despite parents' failure to file timely statement of appellate points, due process required that they be allowed to appeal complaining of ineffective assistance of counsel; "section 263.405(i) is unconstitutional as applied when it precludes a parent from raising a meritorious complaint about the insufficiency of the evidence supporting the termination order"). We reach the same conclusion here: the statute's time limits cannot foreclose an attack by a parent who was deprived of constitutionally adequate notice.27

III. A parent who learns that her rights have been terminated cannot unreasonably delay in seeking to have them reinstated, if vacating the judgment would impair another party's substantial interest in reliance on that judgment.

While actual notice of ongoing proceedings cannot substitute for proper service,28 a parent's right to challenge a termination judgment must have bounds. Under the Restatement, a party may not challenge an invalid default judgment if, (1) after receiving actual notice of the judgment, she manifested an intention to treat the judgment as valid; and (2) granting relief would impair another person's substantial interest of reliance on the judgment. 2 RESTATEMENT (SECOND) OF JUDGMENTS, § 66. As one comment explains:

Id. § 65 cmt. c (emphasis added). Few judgments have more substantial future ramifications than those affecting parentage.

And even though the Supreme Court has never addressed the precise question before us, it has consistently highlighted the defendant's prompt action upon learning of an adverse judgment, even when service by publication violated the defendant's due process rights. See, e.g., Mennonite, 462 U.S. at 794-95, 103 S.Ct. 2706 (noting that Mennonite "did not realize that the property had been sold" and "first learned of the tax sale" just three months before suing to set it aside); Schroeder, 371 U.S. at 210-11, 83 S.Ct. 279 (stating that claimant alleged that "she had never been notified of the condemnation proceedings, and knew nothing about them, nor of her right to make a claim against the city for damages to her property" until a few months before she filed suit); Walker, 352 U.S. at 114, 77 S.Ct. 200 (observing that petition alleged that landowner "had never been notified of the condemnation proceedings and knew nothing about them until after the time for appeal had passed"); see also Greene, 456 U.S. at 446-47, 102 S.Ct. 1874 (noting that, despite notice by posting, defendants did not learn of eviction proceedings until "after default judgments had been entered against them, and after their opportunity for appeal had lapsed"); Armstrong v. Manzo, 380 U.S. 545, 548, 85 S.Ct. 1187, 14 L.Ed.2d 62 (1965) (noting that natural father "promptly filed a motion... asking that the adoption decree be `set aside'" once he learned that his child had been adopted).

The Supreme Court has also suggested that reliance interests in a parental rights case may be relevant even when the defendant's due process rights were clearly breached. See Rothstein v. Lutheran Social Servs., 405 U.S. 1051, 92 S.Ct. 1488, 31 L.Ed.2d 786 (1972). After deciding in Stanley v. Illinois29 that an unwed father was entitled to a hearing before his parental rights were terminated, the Court vacated a Wisconsin Supreme Court decision to the contrary. Id. at 1051, 92 S.Ct. 1208. The Court remanded to the Wisconsin courts for reconsideration of the father's rights in light of Stanley, with instructions to provide "due consideration for the completion of the adoption proceedings and the fact that the child has apparently lived with the adoptive family for the intervening period of time." Id.

Although courts have variously referred to a parent's inaction as waiver, estoppel, or laches, the theories merge: when a child's welfare hangs in the balance, the reliance interest created by a termination order need not yield when a parent learns of the order yet unreasonably fails to act.30 Unlike a judgment debtor who hopes to avoid collection efforts on a money judgment, a parent whose rights have been terminated has every incentive to promptly seek reinstatement upon learning of the termination. "[A] failure to protest the judgment in such a situation can be taken as an affirmation of the judgment because the circumstances invite[] an expression of a contrary position." 2 RESTATEMENT (SECOND) OF JUDGMENTS, § 66 cmt. b. Thus, while we have held that a judgment debtor's post-judgment diligence may be irrelevant in cases involving a default judgment for money damages,31 we cannot reach the same conclusion here.32

If, after learning that a judgment has terminated her rights, a parent unreasonably stands mute, and granting relief from the judgment would impair another party's substantial reliance interest, the trial court has discretion to deny relief. Here, although L.R. learned that her rights were terminated, she provided no information about when she learned of the termination order or what actions she took in response. The record is notably silent on the point. On remand, the trial court should explore this issue.33

IV. Conclusion

The Department's allegations against L.R. are serious, and if proven, may justify terminating her parental rights. But that determination cannot be made before she is given notice and the opportunity to be heard. Service by publication deprived L.R. of due process. She is entitled to a new trial unless she unreasonably delayed in seeking relief after learning of the judgment against her, and granting relief would impair another party's substantial reliance on the judgment. We reverse the court of appeals' judgment and remand to the trial court for further proceedings consistent with this opinion. TEX.R.APP. P. 60.2(d).

Justice LEHRMANN, concurring.

Justice LEHRMANN, concurring.

On rehearing, the State contends that the Court's decision that service by publication in this case failed to comport with due process is faulty because L.R. had appeared at several hearings. Normally, if a defendant appears in open court, the appearance has "the same force and effect as if the citation had been duly issued and served as provided by law." TEX.R. CIV. P. 120. In this instance, though, L.R. never appeared in court after the State's petition to terminate her parental rights had been filed. See TEX. FAM.CODE § 102.009(a)(7). Accordingly, I concur with the Court's order denying the State's motion for rehearing.