The waiver provision in Rule 67(e) provides a constitutionally significant limitation on Rule 67(d), thereby preventing any facially invidious classification related to the financial status of the litigants. Even when a defendant establishes grounds for the security for costs, such requirement must be waived if the plaintiff proves he cannot afford to pay the security. Ariz. R. Civ. P. 67(e). Put differently, Rule 67(d) does not unconstitutionally prohibit a plaintiff's access to the courts because, in accordance with Rule 67(e), if the plaintiff establishes an inability to give the security, the court must vacate the order requiring the security. See Browning v. Corbett, 153 Ariz. 74, 77, 734 P.2d 1030, 1033 (App. 1986) (finding the filing fee in question did not prohibit access to courts because indigent litigant could obtain a waiver). In providing for a waiver, the Rule insures that "one party's economic interest in receiving its costs of litigation should it win" does not unconstitutionally deny a litigant access the courts. Baltayan v. Getemyan, 90 Cal. App. 4th 1427, 110 Cal. Rptr. 2d 72, 84 (Ct. App. 2001). Moreover, Rule 67(d) is reasonably calculated to achieve its legitimate purpose and does not suffer from the constitutional defects of the statutes in Eastin and New. The purpose of the statutes in Eastin and New was to deter frivolous litigation. Tahtinen, 130 Ariz. at 515, 637 P.2d at 725. The bonds at issue in those cases, however, essentially barred some meritorious claims based on the financial status of the litigant. Id. In contrast, Rule 67 does not mandate a bond in every civil case and applies only upon a showing that a plaintiff lacks property in the state that can be readily attached to satisfy a costs judgment. The Rule provides security in light of the difficulty of enforcing a judgment for costs against a person who does not own property within the state. See Alshafie v. Lallande, 171 Cal. App. 4th 421, 89 Cal. Rptr. 3d 788, 794 (Ct. App. 2009) (analyzing a similar costs bond provision). The amount set under Rule 67 is not pre-determined, but rather is reasonably calculated based on the estimated costs of litigation. Because Rule 67 rationally furthers a legitimate state interest and, when properly applied, does not unconstitutionally infringe on fundamental rights or create an invidious classification, the Rule does not violate the Equal Privileges and Immunities Clause of the Arizona Constitution. In Eastin v. Broomfield, 116 Ariz. 576, 570 P.2d 744 (1977), the Arizona Supreme Court considered a statute requiring a plaintiff to post a $2,000 cost bond in order to proceed to trial after an adverse finding by the medical liability review panel. 116 Ariz. at 585, 570 P.2d at 753. The statute prohibited the court from waiving the bond requirement. Id. at 586, 570 P.2d at 754. Similarly, in New v. Ariz. Bd. of Regents, 127 Ariz. 68, 618 P.2d 238 (App. 1980), the statute required a plaintiff to post a $500 cost bond to file a breach of contract or negligence claim against the state. 127 Ariz. at 68-69, 618 P.2d at 238-39. In each case, the court held the cost bond requirement unconstitutional because it denied plaintiffs' access to the court system. Eastin, 116 Ariz. at 586, 570 P.2d at 754; New, 127 Ariz. at 70, 618 P.2d at 240. The Equal Privileges and Immunities Clause, however, does not bar all cost bonds or filing fees. Tahtinen v. Superior Court, 130 Ariz. 513, 515, 637 P.2d 723, 725 (1981). In Tahtinen, the Arizona Supreme Court held that "unless a fundamental right is violated or an invidious classification is created, a statute impinging on the equal privileges and immunities of a class of Arizona residents will be upheld if it has a rational basis." Id. A statute or rule has a rational basis "when it rationally furthers a legitimate legislative purpose." Id.