WOLLHEIM, J.

Plaintiff appeals a limited judgment dismissing for a third time her product liability claims against defendants Genzyme Corporation and Valleylab, Inc.1 Plaintiff, whose claims against those defendants had originally been filed in 2000 and subsequently dismissed as time barred, refiled those claims under a "revival" statute that the legislature enacted in 2003. See Or. Laws 2003, ch. 768, § 2, compiled as a note after ORS 30.905 (2003); Fox v. Collins, 213 Or.App. 451, 453, 162 P.3d 998, rev. den., 343 Or. 223, 168 P.3d 1154 (2007). Defendants moved for summary judgment, asserting that the revival statute was unconstitutional. The trial court agreed and dismissed the revived case. On appeal, we relied on the Oregon Supreme Court's decision in McFadden v. Dryvit Systems, Inc., 338 Or. 528, 535, 112 P.3d 1191 (2005) that "the 2003 amendment to ORS 30.905, reviving certain product liability claims that earlier had been dismissed as untimely, does not violate Article VII (Amended), section 1, of the Oregon Constitution[,]" to conclude that the trial court had erred and remanded the case. On remand, defendants again sought summary judgment, this time asserting that plaintiff's claims were barred by the statute of limitations and did not meet the requirements of the revival statute. The trial court agreed and again dismissed plaintiff's claims against defendants. We affirm.

To provide context, in our first opinion in this case, we reviewed the changes to ORS 30.905(2), the statute of limitations for product liability claims. That background information is also helpful here:

Fox, 213 Or.App. at 453-54, 162 P.3d 998.2

We also set forth the undisputed underlying facts of the case:

Id. at 455-56, 162 P.3d 998 (footnotes omitted). Defendants did not file responsive pleadings. Instead,

Id. at 456, 162 P.3d 998. As noted, in light of McFadden, which had been decided after the trial court granted summary judgment, we concluded that the court had erred in holding the revival statute unconstitutional. Defendants advanced three alternative bases for this court to affirm the trial court's decision:

Fox 213 Or.App. at 458, 162 P.3d 998. We declined to affirm based on any of the alternate grounds proposed by defendants and reversed and remanded the case to the trial court.

Following that remand, defendants filed answers and affirmative defenses to plaintiff's complaint. Among other things, defendants asserted as affirmative defenses that plaintiff's refiled claims were barred by the applicable statute of limitations and were not saved by the revival statute because plaintiff had not complied with that law's requirements. Defendants sought summary judgment on the basis of those arguments. In response, plaintiff asserted that defendants had waived the defenses at issue and that, in any event, we had considered and rejected defendants' assertions in our first opinion and that defendant was bound by our earlier decision as the "law of the case." The trial court agreed with defendants and granted the motions for summary judgment, stating:

Accordingly, the trial court again entered a limited judgment dismissing plaintiff's product liability claims against defendants.

In her single assignment of error on appeal, plaintiff contends that the trial court improperly granted defendants' motions for summary judgment. At oral argument, she conceded that the refiled claims do not comply with the requirements of the revival statute; however, she contends that defendants "waived entitlement to the procedural requirements of amended ORS 30.905" and that "this court rejected defendants' statutory arguments" in the first appeal and, therefore, the "law of the case" should preclude defendant from "re-litigati[ng] * * * the issue." (Boldface omitted.) Defendants, in turn, assert that plaintiff's complaint was time barred and was filed before the effective date of the amendments to ORS 30.905, that they did not waive that defense, and that this court did not decide the issue in its first opinion in this case.

We turn first to plaintiff's "law of the case" argument. According to plaintiff, when we rejected defendants' alternate basis for affirmance in our first opinion, we established the "law of the case" as to that issue; therefore, defendants should not have prevailed on summary judgment. We are not persuaded.

The Oregon Supreme Court has described the "law of the case" doctrine as follows:

State v. Pratt, 316 Or. 561, 569, 853 P.2d 827, cert. den., 510 U.S. 969, 114 S.Ct. 452, 126 L.Ed.2d 384 (1993) (quoting Simmons v. Wash. F. N. Ins. Co., 140 Or. 164, 166, 13 P.2d 366 (1932)). In other words, the "law of the case" doctrine gives "preclusive effect to legal rulings made or sustained in prior appeals in the same litigation[.]" Poet v. Thompson, 208 Or.App. 442, 450, 144 P.3d 1067 (2006). However,

Hayes Oyster Co. v. Dulcich, 199 Or.App. 43, 53-54, 110 P.3d 615, rev. den., 339 Or. 544, 125 P.3d 750 (2005) (internal quotations marks and citations omitted).

Here, as plaintiff correctly points out, in our first opinion in this case we declined defendants' invitation to affirm the trial court on the alternate ground "that plaintiff's claims do not qualify for revival under the statute, either because no final judgment was entered previously, or because plaintiff refiled her claims too early[.]" Fox, 213 Or.App. at 459, 162 P.3d 998. We held that "the revival statute incorporates into ORS 30.905(2) the equivalent of a statute of limitations for the purpose of bringing a revived products liability claim[,]" id. at 460, 162 P.3d 998 (emphasis in original), and observed that a statute of limitations defense "`is waived if it is neither made by motion under [ORCP 21] nor included in a responsive pleading or an amendment thereof.'" Id. at 459, 162 P.3d 998 (quoting ORCP 21 G(2)). We then reasoned as follows:

Id. at 460-61, 162 P.3d 998 (emphasis added; omitted). In that discussion, we did not fully consider and reject defendants' arguments on their merits as plaintiff contends. Instead, we declined to consider them as an alternate basis to affirm the trial court's ruling. As we stated, before we can affirm a trial court's decision on alternate grounds, the record must be sufficient to support such an affirmance. In the absence of a responsive pleading or motion to dismiss raising the statute of limitations, the trial court could not have dismissed the case based on such a defense.3 And, because neither such a motion nor a responsive pleading had been filed before the court granted summary judgment based on defendants' constitutional arguments, it remained to be seen whether the defense would actually be properly raised by defendants. Thus, we concluded that the record in the case, as it existed at that time, was not sufficient to support affirmance on that basis. We did not fully consider and resolve defendants' statutory arguments in the disposition of the prior appeal. Accordingly, plaintiff's reliance on the "law of the case" doctrine is unavailing.

As noted, plaintiff also contends, as she did in the first appeal, that "[d]efendants waived entitlement to the procedural requirements of amended ORS 30.905." (Boldface omitted.) Specifically, she states that

Defendant responds first that "[b]ecause plaintiff's complaint was untimely on its face, the burden was on her to show that her claims were nonetheless `revived' by amended ORS 30.905, and not on defendant to establish that her claims were not revived."5 (Boldface omitted.) Second, according to defendants, "[t]he record establishes as a matter of law that defendant did not waive the statute of limitations. The Oregon Rules of Civil Procedure specify the ways in which a statute of limitations may be waived." That is, pursuant to ORCP 21 G(2), such a defense is waived "if it is neither made by motion under [that] rule nor included in a responsive pleading or an amendment thereof." Here, defendant "filed no motion to dismiss under ORCP 21 and it filed no responsive pleading which omitted the defense."6

As noted, according to plaintiff, by virtue of the original motion for summary judgment on the refiled claims (the original motion) in which it argued that the revival statute was unconstitutional, defendants waived the right to assert that plaintiff's claims failed to meet the requirements of the revival statute. In plaintiff's view, not only did defendants fail to raise the issue in the original motion, but they also "affirmatively stated that plaintiff's claims were procedurally proper[.]" (Emphasis added.) Again, we are unpersuaded.

Under Oregon law, waiver is the "intentional relinquishment of a known right." Johnson v. Swaim, 209 Or.App. 341, 346, 147 P.3d 374 (2006), aff'd, 343 Or. 423, 172 P.3d 645 (2007) (internal quotation marks omitted). Such a waiver "must be plain and unequivocal, either in its terms or by conduct, clearly indicating an intention to renounce a known privilege or power." Id. As noted, where a defendant files a motion to dismiss pursuant to ORCP 21 or a responsive pleading, and fails to include therein a statute of limitations defense, that defense is deemed waived as a matter of law.7 See ORCP 21 G(2) ("A defense * * * that the action has not been commenced within the time limited by statute, is waived if it is neither made by motion under this rule nor included in a responsive pleading or an amendment thereof.").

Here, defendants filed no responsive pleadings or motions to dismiss pursuant to ORCP 21 before filing the original motion for summary judgment and thus, did not trigger the waiver provision in ORCP 21 G(2). Instead, after being served with the complaint, defendants immediately sought summary judgment asserting that the statute was unconstitutional. That procedure was permissible under the rules. See ORCP 15 A ("A motion or answer to the compliant * * * shall be filed with the clerk by the time required by Rule 7 C(2) to appear and defend." (Emphasis added.)); ORCP 47 B ("A party against whom a claim * * * is asserted * * * may, at any time, move, with or without supporting affidavits or declarations, for a summary judgment in that party's favor[.]"). Nothing in the Oregon Rules of Civil Procedure requires that, in general terms, every defense or basis for summary judgment be included in such a motion. Nor do the rules provide, specifically, that if a summary judgment motion does not include a statute of limitations defense, that defense is waived. Furthermore, plaintiff has not pointed to some other source creating such a requirement, nor are we aware of any. Accordingly, we reject plaintiff's argument that defendants waived the defense at issue simply by virtue of failing to include it in the original motion for summary judgment.

We are likewise unconvinced that defendants ever "affirmatively" represented that plaintiff's claims were properly before the court pursuant to the revival statute. Indeed, plaintiff acknowledged as much at oral argument in this appeal, and took the position that defendants' assertions to the trial court nonetheless indicated that the claims were procedurally proper. In arguing that the revival statute was unconstitutional, defendants stated several times that a final judgment had previously been entered dismissing plaintiff's product liability claims with prejudice and observed that the revival statute "appears to grant plaintiff legislative permission to re-litigate" those claims. In our view, defendants' assertions in the original motion do not imply that plaintiff's refiled claims are procedurally proper under the revival statute. In fact, defendants stated only that the terms of the statute appeared to permit plaintiff the ability to re-litigate claims that had already been resolved. Those arguments, in the context of defendants motion for summary judgment, do not amount to the intentional relinquishment of a known right; they were provided as context for the constitutional arguments that defendants were making and were not an unequivocal renunciation of the ability to later raise the defense at issue.

In light of the foregoing, we conclude that the trial court did not err in granting summary judgment in favor of defendants.

Affirmed.