specially concurring:
The writer of the court’s opinion deems it necessary to complete the record in order to point out why, in writing for the court, he said nothing about the injunctive relief contained in the district court’s summary judgment order.
The district court correctly declared that the permanent presence of the disputed crosses on public property violates the No Preference Clause of the California Constitution. However, San Diego County claims that the Mt. Helix Cross has been transferred to the San Diego Historical Society. Likewise, the City of San Diego claims it is authorized to transfer the Mt. Soledad Cross. The plaintiffs claim that both actions thwart the injunctive relief granted by the district court.
These matters involve enforcement of the injunction and must first be considered by the district court. The district court, however, did not explicitly state the manner in which its injunction was to be enforced.1 Given their dissatisfaction with the property transfers, one can suppose the plaintiffs will call upon the district court to enforce the injunction by requiring the removal or destruction of the crosses. Destruction of the crosses, however, raises as many issues as it resolves.
A. The Mt. Helix Cross Conveyance
The original 1929 Yawkey deed that conveyed the land and the Mt. Helix Cross to the County contained a reversionary clause.2 No Yawkey heirs were made party to this action in the district court.3 As noted above, the County claims to have conveyed title to the Mt. Helix Cross and a thirty-foot diameter circle of land beneath it to the San Diego Historical Society. The validity of this conveyance raises a variety of issues involving California property and trust law.
As an initial matter, it is unclear whether the County validly took title of the land in the first place. A municipal corporation cannot ordinarily act as trustee of property to be devoted solely to religious uses. See Eugene McQuillin, 10 The Law of Municipal Corporations, § 28.31 (3rd ed. 1990). If the County cannot act as trustee under the Mt. Helix conveyance, then either the reversionary clause of the conveyance applies, or the court may prevent the trust from failing by appointing a private trustee. See id. at § 28.36.
The reverter clause may no longer be applicable.4 However, the plaintiffs con*1530cede that the Yawkey heirs may have an interest if 1) the court finds the original deed created a charitable trust and 2) the actions taken by the County are determined to have caused such trust to fail.5
Although the district court noted that “San Diego County is the trustee” of the “funds left in trust ... for the purpose of maintaining the Mt. Helix Nature The-atre,” 6 the court did not determine whether the real property itself is held by the County in trust. A number of issues, then, have yet to be resolved. These include determining whether a trust exists, who are the interested parties under that trust, the existence and effect of the reversionary clause, and what effect the County’s transfer has on the trust.
The injunction forbids “the permanent presence of each cross on the public property ... where it appears,” and gives the defendants three months to comply with the court’s order.7 It seems to me there are but two ways to comply with this order; the County must either transfer the land or destroy the crosses. Both alternatives implicate the rights of parties not before the court and involve issues undecided by the court. Before the County may transfer the land, it must have title to the land. As noted above, there has been no determination that the initial conveyance to the County was valid in the first place. For similar reasons, the County cannot remove the crosses without potentially violating the property rights of the Heirs of Yawkey who may have legal title to both the land and the cross. If enforcement proceedings are initiated in the district court, questions of California property law and the joinder of interested parties will undoubtedly be at issue.8
B. The Mt. Soledad Cross
The voter authorization to transfer ownership of Mt. Soledad Cross has no effect on the court’s determination today that the status quo violates the California Constitution. As the opinion points out, a challenge to any future transfer should be brought first before the district court.
A more difficult question is whether all parties who have a legal interest in the Mt. Soledad Cross were before the district court when it issued its injunction. The City argues that the Mt. Soledad Cross is owned by the Mt. Soledad Memorial Association and that the interests of the Association were not considered by the district court. According to the City, removing the cross would violate the Association’s property rights under state and federal law. Plaintiffs argue that the Association has no legal interest in this litigation because the cross was given to the City as a gift.
Under Federal Rule of Civil Procedure 19(a), a just adjudication requires, if feasible, the joinder of those parties that have “a legally cognizable interest in the suit, and [whose] interest will be impaired or impeded by the suit....” Makah Indian Tribe v. Verity, 910 F.2d 555, 558-59 (9th *1531Cir.1990). See also Shimkus v. Gersten Companies, 816 F.2d 1318, 1322 (9th Cir.1987) (the need to consider the interests of third parties, and to do so in the same litigation, favors a decision to require join-der).
In this case, absent a finding by the district court as to who actually owns the cross, it remains unclear whether all “interested parties” were before the district court when it issued its injunction. As with the Mt. Helix Cross, this is a question of state law and may require the joinder of additional interested parties.
When the mandate issues, proceedings to enforce the injunction may be initiated in the district court. The district court, of course, has continuing power to modify or vacate its decree. See System Fed’n No. 91, Ry. Employes’ Dep’t, AFL-C10 v. Wright, 364 U.S. 642, 647, 81 S.Ct. 368, 371, 5 L.Ed.2d 349 (1961) (“There is ... no dispute but that a sound judicial discretion may call for the modification of the terms of an injunctive decree if the circumstances, whether of law or fact, obtaining at the time of its issuance have changed, or new ones have since arisen.”). See also 11 Charles Allen Wright & Arthur R. Miller, Federal Practice and Procedure § 2961 (1973) (noting the “universally recognized principle that a court has continuing power to modify or vacate a final decree”). Upon hearing the claims of the parties, the district court will be able to modify, fashion or enforce appropriate equitable relief as the constitutional and property interests of the respective parties may be determined.
. See ante, at note 7.
. The clause reads as follows:
AND IT IS FURTHER PROVIDED, That ... should [the County] ... convey, or attempt to convey ... said premises herein conveyed, or any part or parcel thereof, ... to any person, firm association, organization, or corporation, ... then and in that event, the said premises, and the whole thereof, and said fund and/or funds, and the whole thereof, ... shall forthwith revert to, and the title thereof and thereto vest in, and the whole thereof become the property of the trustor herein, his heirs and assigns, and the heirs and assigns of ... MARY YAWKEY WHITE, Deceased, as fully as if these presents had never been executed.
. The district court explicitly declined to address the reversionary interest issue. Murphy, 782 F.Supp. at 1434 n. 36 ("The present lawsuit poses constitutional issues only. It does not provide a sufficient legal or evidentiary basis from which to rule on the sufficiency and application of the deed’s reversionary clause.”).
. The County argues that, under the Marketable Record Title Act, Cal.Civil Code §§ 885.010, 885.020 (1982), the power of termination expired unless a notice of intent to preserve the power to terminate was recorded within five years after the operative date of the Act. See id. at §§ 880.030, 880.370. I express no opinion on whether the power to terminate has in fact expired.
. Where property is given in trust, but the trust fails for some reason, a resulting trust arises in favor of the grantor or his successors. Witkin, Summary of California Law, "Trusts” § 298 (9th ed. 1990); Restatement (Second) of Trusts § 335. See e.g. Evans v. Newton, 221 Ga. 870, 148 S.E.2d 329 (1966), aff’d sub nom, Evans v. Abney, 396 U.S. 435, 90 S.Ct. 628, 24 L.Ed.2d 634 (1970) (where sole purpose for which the trust had been created had become impossible of accomplishment, the charitable trust has been terminated and a resulting trust is implied for the benefit of the grantor or his heirs).
. Murphy, 782 F.Supp. at 1423 n. 8.
. It should be noted that stays have been issued pending the outcome of this appeal. See Paulson v. City of San Diego, No. 92-55087 (9th Cir. April 1, 1992) (ere banc); Ellis v. City of La Mesa, No. 92-55086 (9th Cir. Mar. 19, 1992); Murphy v. Bilbray, No. 92-55093 (9th Cir. Mar. 19, 1992). These stays will remain in effect until the mandate of this court issues, usually twenty-one days after this opinion is filed. See Fed.R.App.P. 41(a).
. It bears pointing out that, along with any Yawkey heirs, the interests of the San Diego Historical Society should be considered on remand. As the current holders of colorable title to both the cross and the surrounding land, the Society clearly has an interest in the outcome of this litigation.