Alexander, J.
— Kay and Norma Lybbert brought suit against Grant County (hereinafter County) for personal injuries they allegedly sustained in an automobile accident on a Grant County road. The County thereafter moved for a summary judgment dismissing the Lybberts’ suit, contending that service of process by the plaintiffs was defective. The trial court agreed with the County and dismissed the suit, concluding that the plaintiffs failed to properly serve their summons and complaint on the County within the [32]*32applicable statute of limitations. The Court of Appeals reversed the trial court, holding that the County was not entitled to rely on the affirmative defense of insufficient service of process because (1) it had waived the defense and/or (2) was equitably estopped from asserting it. We granted the County’s petition for review and now affirm the Court of Appeals on the basis that the County waived the defense of insufficient service of process.
The Lybberts claim that they were both injured in early 1993 when their automobile struck a hole in a Grant County road. On August 30, 1995, the Lybberts filed a summons and complaint in the Adams County Superior Court in which they sought damages from the County for the injuries they contend they sustained as a consequence of the County’s alleged failure to maintain its roadway in a safe condition.1 Pursuant to RCW 4.28.080(1), the Lybberts were required to serve their summons and complaint on the County auditor.2 They mistakenly served process on the administrative assistant to the County commissioners. Nonetheless, a few days after the “service,” counsel for the County filed a notice of appearance in which it was indicated that the County was not “waiving objections to improper service or jurisdiction.” Clerk’s Papers (CP) at 13.
For the next nine months the County acted as if it were preparing to litigate the merits of the case that the Lybberts were attempting to mount against it. For example, shortly after filing its notice of appearance the County served the Lybberts with interrogatories, requests for production, and a request for a statement setting forth general and special damages. In this discovery effort, the County made no inquiry regarding the sufficiency of the service of process. [33]*33The County also associated counsel from an outside law firm and duly filed a “notice of association of counsel.” CP at 15. Thereafter, one of the attorneys for the County had conversations over the telephone with the Lybberts’ attorney about insurance coverage and potential mediation. During these contacts, the attorney for the County did not make any mention of an issue surrounding sufficiency of the service of process. The Lybberts’ attorney claims that one of the attorneys for the County told him that the County was working on its answer to the complaint and that it would be provided “as soon as possible.” CP at 30.
On February 29, 1996, the Lybberts’ attorney served one of the attorneys for the County with interrogatories and a request for production of documents. One interrogatory asked the County whether it would be relying on the affirmative defense of insufficient service of process.3 In April of 1996, a County sheriffs detective, ostensibly acting on behalf of the County, contacted the Lybberts’ attorney in order to ascertain what type of information the Lybberts were requesting in their interrogatories. According to an affidavit from the Lybberts’ attorney, the detective said that the County would fully cooperate in providing all of the requested discovery information.
On May 6, 1996, the Lybberts responded to the County’s interrogatories, as well as to its requests for production and statement of damages. On June 21, 1996, the County filed its answer to the Lybberts’ complaint and asserted, for the first time, the affirmative defense of insufficient service of process. The County then filed a motion for summary judgment, based on the alleged insufficient service of process, and requested that the case against it be dismissed on the ground that the applicable statute of limitations had [34]*34run on the Lybberts’ claim.4 The trial court granted the County’s motion and dismissed the Lybberts’ complaint with prejudice. The Lybberts appealed to Division Three of the Court of Appeals. The Court of Appeals reversed the trial court, holding that the County waived the defense of insufficient service of process and was equitably estopped from asserting it. We granted the County’s petition for review.
DISCUSSION
I. Scope of Review
On appeal of summary judgment, the standard of review is de novo, and the appellate court performs the same inquiry as the trial court. Nivens v. 7-11 Hoagy’s Corner, 133 Wn.2d 192, 197-98, 943 P.2d 286 (1997). When ruling on a summary judgment motion, the court is to view all facts and reasonable inferences therefrom most favorably toward the nonmoving party. Weyerhaeuser Co. v. Aetna Cas. & Sur. Co., 123 Wn.2d 891, 897, 874 P.2d 142 (1994). A court may grant summary judgment if the pleadings, affidavits, and depositions establish that there is no genuine issue as to any material fact and the moving party is entitled to judgment as a matter of law. Ruff v. King County, 125 Wn.2d 697, 703, 887 P.2d 886 (1995); see also CR 56(c).
The County argues that the Court of Appeals’ decision, with respect to waiver and equitable estoppel, conflicts with precedent from this court as well as case law from Divisions One and Two of the Court of Appeals. The Lybberts counter that if this court concludes that the County waived the defense of insufficient service of process or is equitably [35]*35estopped from asserting it, such a conclusion would be consonant with the cases from this court as well as cases from Divisions One and Two of the Court of Appeals. We discuss both equitable estoppel and waiver in turn.
II. Equitable Estoppel
The Lybberts argue here, as they did at the Court of Appeals, that the County is equitably estopped from asserting the defense of insufficient service of process. Equitable estoppel is based on the notion that “a party should be held to a representation made or position assumed where inequitable consequences would otherwise result to another party who has justifiably and in good faith relied thereon.” Kramarevcky v. Department of Soc. & Health Servs., 122 Wn.2d 738, 743, 863 P.2d 535 (1993) (quoting Wilson v. Westinghouse Elec. Corp., 85 Wn.2d 78, 81, 530 P.2d 298 (1975)). The elements of equitable estoppel are: “(1) an admission, statement or act inconsistent with a claim afterwards asserted, (2) action by another in [reasonable] reliance upon that act, statement or admission, and (3) injury to the relying party from allowing the first party to contradict or repudiate the prior act, statement or admission.” Board of Regents v. City of Seattle, 108 Wn.2d 545, 551, 741 P.2d 11 (1987). Where both parties can determine the law and have knowledge of the underlying facts, estoppel cannot lie. Chemical Bank v. Washington Pub. Power Supply Sys., 102 Wn.2d 874, 905, 691 P.2d 524 (1984). Equitable estoppel must be shown “by clear, cogent, and convincing evidence.” Berschauer/Phillips Constr. Co. v. Seattle Sch. Dist. No. 1, 124 Wn.2d 816, 831, 881 P.2d 986 (1994).
We are satisfied that the Lybberts have established two of the elements of equitable estoppel. In that regard, it is readily apparent that the County acted in a way that was inconsistent with its eventual assertion of the defense of insufficient service of process. For nine months following its attorneys’ appearance in response to the Lybberts’ duly [36]*36filed summons and complaint, the County gave multiple indications that it was preparing to litigate this case. Only after the statute of limitations appeared to have run on the Lybberts’ claim did it raise the affirmative defense of insufficient service of process. Furthermore, allowing the County to assert the defense of insufficient service of process after the statute of limitations has run would be injurious to the Lybberts because they would be without a forum in which to pursue their claim against the County.
We are satisfied, though, that the Lybberts have not established that they justifiably relied on the actions of the County’s counsel. We reach that conclusion because the statute governing service of process on counties is explicit in specifying that the county auditor is the person who is to be served with process. RCW 4.28.080(1). Given the clear statutory mandate to serve the county auditor, it was not at all reasonable, much less justifiable, for the Lybberts to rely on the County’s failure to expressly claim, prior to the expiration of the statute of limitations, that the service upon it was ineffective. See Overhulse Neighborhood Ass’n v. Thurston County, 94 Wn. App. 593, 972 P.2d 470 (1999) (holding unambiguous mandate of statutory service provisions made reliance unreasonable); Davidheiser v. Pierce County, 92 Wn. App. 146, 154, 960 P.2d 998 (1998) (rejecting equitable estoppel claim because clarity of statutory provision precluded any reasonable reliance), review denied, 137 Wn.2d 1016, 978 P.2d 1097 (1999); Landreville v. Shoreline Community College Dist. No. 7, 53 Wn. App. 330, 332, 766 P.2d 1107 (1988).
The Landreville case, with which we are in agreement, is particularly illustrative of the point that the Lybberts’ reliance was not justifiable. There a process server left a copy of the summons and complaint with an administrative assistant to the attorney general despite the fact that the statute pertinent to that case required that service be made upon the attorney general. The plaintiff argued there that the defendant should be estopped from asserting the defense of insufficient service of process because the attorney [37]*37general’s administrative assistant represented that she had authority to accept service of process. The Landreville court disagreed with that argument, holding that because of the clear language of the service statute it was unreasonable for the plaintiff to rely on the actions of the attorney general’s assistant. The Lybberts argue that Landreville is distinguishable because there the plaintiffs were relying on the actions of an administrative assistant rather than the actions of the defendant’s counsel, as was the case here. This appears to us to be a distinction without a difference. The fact remains that in the instant case, as in Landreville, a statute explicitly indicates who is to be served with process. In light of the clarity of the statute, any reliance on action or inaction on the part of either or both of the County’s counsel is not justifiable.
Before leaving this issue, we note that in resolving the equitable estoppel issue in favor of the Lybberts, the Court of Appeals placed emphasis on what it described as a duty on the part of the government to conduct litigation “in a manner above reproach” and to be “scrupulously just in dealing with its citizens.” Lybbert v. Grant County, 93 Wn. App. 627, 634, 969 P.2d 1112, review granted, 138 Wn.2d 1001, 984 P.2d 1034 (1999). In light of that duty, the court opined, counsel for the County “should have raised the issue of insufficient service prior to the expiration of the statute of limitations.” Lybbert, 93 Wn. App. at 634. While we agree with the basic proposition that the government should be just when dealing with its citizens,5 we do not believe that an attorney representing the government has a duty to maintain a standard of conduct that is higher than that expected of an attorney for a private party. If we were [38]*38to impose such a heightened duty on attorneys for the government we would be creating a two-tiered system of advocacy, one for legal representatives of the government and the other for counsel of private parties. We are loath to do so, particularly in light of the generally recognized view, embodied in the Preliminary Statement to the Rules of Professional Conduct, to the effect that “the rules should be uniformly applied to all lawyers, regardless of the nature of their professional activities.” Washington Court Rules 34 (2000) (emphasis added).
In sum, even after viewing the evidence in the light most favorable to the Lybberts, we are satisfied that they have not established the element of justifiable reliance by clear, cogent, and convincing evidence. Therefore, the County is not equitably estopped from asserting the defense of insufficient service of process. This does not mean, however, that the defense is available to the County if it was waived. That is the issue to which we now turn.
III. Waiver
The Lybberts, citing the common law doctrine of waiver, claim that the County is precluded from asserting the defense of insufficient service of process because it acted in an inconsistent and dilatory manner. This court has discussed the doctrine of waiver in this context on only one occasion. See French v. Gabriel, 116 Wn.2d 584, 806 P.2d 1234 (1991). In that case we recognized the viability of the doctrine, but concluded that under the facts of that case the defendant had not waived the defense. Significantly, all three divisions of the Court of Appeals of this state have also recognized the common law doctrine of waiver. See Clark v. Falling, 92 Wn. App. 805, 813, 965 P.2d 644 (1998) (Division One); Davidheiser v. Pierce County, 92 Wn. App. 146, 155, 960 P.2d 998 (1998), review denied, 137 Wn.2d 1016, 978 P.2d 1097 (1999) (Division Two); Romjue v. Fairchild, 60 Wn. App. 278, 281, 803 P.2d 57, review denied, 116 Wn.2d 1026, 812 P.2d 102 (1991) (Division Three). Under the doctrine, affirmative defenses such as insuffi[39]*39cient service of process may, in certain circumstances, be considered to have been waived by a defendant as a matter of law. The waiver can occur in two ways. It can occur if the defendant’s assertion of the defense is inconsistent with the defendant’s previous behavior. Romjue, 60 Wn. App. at 281. It can also occur if the defendant’s counsel has been dilatory in asserting the defense. Raymond v. Fleming, 24 Wn. App. 112, 115, 600 P.2d 614 (1979) (citing 5 Charles Alan Wright & Arthur R. Miller, Federal Practice And Procedure § 1344, at 526 (1969)), review denied, 93 Wn.2d 1004 (1980).
We believe the doctrine of waiver is sensible and consistent with the policy and spirit behind our modern day procedural rules, which exist to foster and promote “the just, speedy, and inexpensive determination of every action.” CR 1. If litigants are at liberty to act in an inconsistent fashion or employ delaying tactics, the purpose behind the procedural rules may be compromised. We note, also, that the common law doctrine of waiver enjoys a healthy existence in courts throughout the country, with numerous federal and state courts having embraced it. See, e.g., Trustees of Cent. Laborers’ Welfare Fund v. Lowery, 924 F.2d 731, 732 (7th Cir. 1991) (observing that “[a] party may waive a defense of insufficiency of process by failing to assert it seasonably”); Santos v. State Farm Fire & Cas. Co., 902 F.2d 1092, 1096 (2d Cir. 1990); Marcial Ucin, S.A. v. S.S. Galicia, 723 F.2d 994, 997 (1st Cir. 1983); Kearns v. Ferrari, 752 F. Supp. 749, 752 (E.D. Mich. 1990); Burton v. Northern Dutchess Hosp., 106 F.R.D. 477, 481 (S.D.N.Y. 1985); Tuckman v. Aerosonic Corp., 394 A.2d 226, 233 (Del. Ch. 1978); Joyner v. Schiess, 236 Ga. App. 316, 512 S.E.2d 62 (1999).
Despite embracing this doctrine of waiver, we quickly add that the doctrine does not alter the traditional duties litigators owe to their adversaries. Those duties, which are memorialized in the Rules of Professional Conduct (RPC) and refined by case law from this court, remain the same. See RPC 3.4; Sherman v. State, 128 Wn.2d 164, 184-85, 905 P.2d 355 (1995); see also Washington State Physicians Ins. Exch. [40]*40& Ass’n v. Fisons Corp, 122 Wn.2d 299, 858 P.2d 1054 (1993). Our holding today merely underscores the importance of preventing the litigation process from being inhibited by inconsistent or dilatory conduct on the part of litigants.
We are satisfied, in short, that the doctrine of waiver complements our current notion of procedural fairness and believe its application, in appropriate circumstances, will serve to reduce the likelihood that the “trial by ambush” style of advocacy, which has little place in our present-day adversarial system, will be employed. Apropos to the present circumstances of this case, one court has acknowledged that
[a] defendant cannot justly be allowed to lie in wait, masking by misnomer its contention that sendee of process has been insufficient, and then obtain a dismissal on that ground only after the statute of limitations has run, thereby depriving the plaintiff of the opportunity to cure the service defect.
Santos, 902 F.2d at 1096.
In applying the doctrine, we first observe that there are no material facts in dispute.6 It is, therefore, appropriate for this court to apply the doctrine of waiver to the undisputed material facts to determine if the County is precluded from asserting the defense of insufficient service of process in this case. In this process, the well-reasoned decision of the Court of Appeals in Romjue v. Fairchild, 60 Wn. App. 278, is instructive. There, a process server did not make proper service on the defendants. Nevertheless, the defendants’ attorney filed a notice of appearance and subsequently served plaintiff’s attorney with interrogatories and a request for production of documents. The attorney for the plaintiff responded to the discovery requests and then [41]*41served the defendants with his own interrogatories and requests for production of documents. Plaintiff’s attorney also sent a letter to the defendants’ attorney stating, “it is my understanding that the defendants have been served in the above matter [Romjue v. Fairchild].” (alteration in original) (emphasis omitted). Romjue, 60 Wn. App. at 281. The attorney for the defendants did not respond to this letter, but instead waited for the statute of limitations to run and then asserted the defense of insufficient service of process. The issue there, as here, was whether the defendants waived the defense by participating in discovery and failing to assert the defense prior to the expiration of the statute of limitations.
The Romjue court quite properly noted that the mere act of engaging in discovery “is not always tantamount to conduct inconsistent with a later assertion of the defense of insufficient service.” Romjue, 60 Wn. App. at 281. This is so because in some circumstances it may be entirely appropriate for a party to engage in discovery to determine if the facts exist to support a defense of insufficient service. Romjue, 60 Wn. App. at 281; see also Matthies v. Knodel, 19 Wn. App. 1, 5-6, 573 P.2d 1332 (1977) (observing that deposition was taken to find out if defense existed for the defendant). The Romjue court went on to conclude, however, that the defendants’ discovery efforts were inconsistent with the later asserted defense because it was not geared toward elucidating facts relating to a defense of insufficient service of process. The court took particular note of the letter the plaintiff’s attorney sent to the defendants’ attorney, prior to the expiration of the statute of limitations, expressing the plaintiff’s understanding that service of process had been effected on the defendants. The court concluded that by engaging in discovery and ignoring the letter, the defendants waived the defense of insufficient service of process that was asserted only after the time clock had run out.
The County’s conduct was similar to that of the defendants in Romjue. In particular, we note that the County’s [42]*42discovery efforts were not aimed at determining whether there were facts that supported the defense of insufficient service of process. Indeed, because the process server’s affidavit was filed by the plaintiffs, the County knew or should have known that the defense of insufficient service of process was available to it.7 Moreover, the County did more than just undertake discovery. As noted above, its detective contacted Lybberts’ counsel in order to make certain that the County correctly understood the nature and extent of the Lybberts’ interrogatories. Furthermore, there were telephone calls between counsel for the respective parties at which there was a discussion about potential mediation.8 Of particular significance is the fact that the Lybberts served the County with interrogatories that were designed to ascertain whether the defendant was going to rely on the defense of insufficient service of process. Had the County timely responded to these interrogatories, the Lybberts would have had several days to cure the defective service. The County did not answer the interrogatories but instead waited until after the statute of limitations expired to file its answer and for the first time assert the defense.
The County asserts that because the Lybberts were several months tardy in providing answers to the County’s discovery requests, the Lybberts cannot fault it for its delay in answering discovery and asserting the defense. We disagree. The record reveals that the Lybberts’ delay in answering was justified because they “were still actively treating and that complete answers to interrogatories, which were served in October 1995, would be delayed so [43]*43that a complete history of the injuries and damages could be submitted.” CP at 36. This reason stands in stark contrast to that provided by the County, which was that the County “routinely avoid [s] answering a complaint, until a motion for default is brought.” CP at 164.
It is also of no significance to our waiver analysis that the notice of appearance, filed by one of the attorneys for the County, included a statement that counsel was appearing “without waiving objections to improper service or jurisdiction.” CP at 13. That is so because we have said that the mere appearance by a defendant does not preclude the defendant from challenging the sufficiency of service of process. Adkinson v. Digby, Inc., 99 Wn.2d 206, 209, 660 P.2d 756 (1983); see also Matthies, 19 Wn. App. at 4. Thus, even if the caveat had not been included, the County could have challenged the sufficiency of the service of process. In other words, it was not necessary for the County to indicate that it was appearing “without waiving objections to improper service” in order to subsequently challenge the service of process. Since the filing of a notice of appearance without including the caveat cannot constitute a waiver of the defense, we see no reason why filing the notice of appearance with the caveat should serve as a vehicle to preserve it.
According to the dissent, the County did not waive the defense because it “filed a notice of appearance expressly reserving the right to assert the defense of insufficient service of process.” Dissenting op. at 49. To the degree the dissent suggests that a notice of appearance is the functional equivalent of an answer or other responsive pleading, we disagree. The Superior Court Civil Rules (CR) require that the defense of insufficient service of process be brought forth in a pleading. See CR 12(b) (“Every defense .. . shall be asserted in the responsive pleading . . . .”). The rules are quite clear as to what constitutes a pleading. See CR 7(a) (A pleading is one of the following: a complaint, an answer, a reply to a counterclaim, an answer to a cross claim, a third party complaint, and a third party answer.). Absent from this list is a notice of appearance.
[44]*44Finally, the County argues that if we were to affirm the Court of Appeals on the waiver issue, such a decision would conflict with this court’s decision in French v. Gabriel, 116 Wn.2d 584. We disagree, being satisfied that our decision today is in complete harmony with French. In French, the plaintiff argued that the defendant waived the defense of insufficient service of process by filing an untimely answer, objecting to a trial date, taking a deposition, and consenting to amendment of the complaint. The plaintiff also argued that the defendant waived the defense because he delayed in filing his answer to the complaint. We held there was no waiver because the defendant preserved the defense by pleading it prior to objecting to the trial date, taking a deposition, and consenting to amendment of the complaint. French, 116 Wn.2d at 594; see also Voicelink Data Servs., Inc. v. Datapulse, Inc., 86 Wn. App. 613, 625, 937 P.2d 1158 (1997) (participating in substantive discovery did not waive defense since it was pleaded prior to engaging in discovery); Crouch v. Friedman, 51 Wn. App. 731, 735, 754 P.2d 1299 (1988) (raising defense in answer prior to engaging in discovery is sufficient to preserve the defense). Moreover, the answer, although late, was filed more than a year before the statute of limitations extinguished the plaintiff’s claim. Although we expressed displeasure at the defendant’s failure to file a timely answer, we noted that “ ‘mere delay in filing an answer does not constitute a waiver of an insufficient service defense.’ ” French, 116 Wn.2d at 593-94 (quoting French v. Gabriel, 57 Wn. App. 217, 222, 788 P.2d 569, review granted, 114 Wn.2d 1026, 793 P.2d 976 (1990)).
By contrast, here the County failed to preserve the defense by pleading it in its answer or other responsive pleading before proceeding with discovery. Instead, it engaged in discovery over the course of several months and then, after the statute of limitations had apparently extinguished the claim against it, it asserted the defense. French does not remotely stand for the proposition that it is [45]*45acceptable for a defendant to lie in wait, engage in discovery-unrelated to the defense, and thereafter assert the defense after the clock has run on the plaintiff’s cause of action.9
CONCLUSION
For the reasons stated above, we conclude that the County is not equitably estopped from asserting the defense of insufficient service of process. It did, however, by the actions of its representatives waive the defense. We, therefore, affirm the result reached by the Court of Appeals.
Smith, Johnson, Sanders, and Ireland, JJ., and Shields, J. Pro Tern., concur.