Plaintiff Connie Armijo sued defendants Jamie Miles, M.D. (Miles), Labriute Medical Group Incorporated (Labriute) and Sherman Oaks Hospital and Health Center (Sherman Oaks Hospital) for the wrongful death of her domestic partner, Dana Schwartz (Dana).  The trial court sustained defendants’ demurrers to plaintiff’s causes of action, concluding that plaintiff lacked standing to sue under the 2002 version of the wrongful death statute (Stats. 2001, ch. 893, § 2), in that she and Dana had not registered their domestic partnership with the Secretary of State.
 Plaintiff appealed from the order and judgment dismissing her action.  During the pendency of this appeal, and after the parties had filed their briefs, the Legislature amended the wrongful death statute (Stats. 2004, ch. 947, § 1).  Based upon this amendment, which took effect on January 1, 2005 and which applies retroactively to plaintiff’s wrongful death claim, we conclude the facts plaintiff alleged in her operative complaint are sufficient to establish her standing to sue for wrongful death.  Accordingly, we reverse the judgment and remand for further proceedings.

FACTS

Plaintiff and Dana first met in 1987.  After dating for six months, the two women made a decision to be committed to each other exclusively as “life partners and ‘spouses.’”
Plaintiff and Dana jointly were responsible for each other’s living expenses.  During their relationship, neither woman entered into any other relationship or domestic partnership.  They lived with one another, and, in 1998, they purchased a home together, where they resided until Dana’s death.
Plaintiff and Dana were not related by blood in a way that would have prevented them from marrying each another if they could have been married.  Each was over the age of 18 when they met and formed their relationship.
On August 6, 2001, Dana died at defendant Sherman Oaks Hospital, where she had been “hospitalized for pain management and associated rehabilitation.”  Miles, an employee of Labriute, had been Dana’s physician.

PROCEDURAL BACKGROUND

On August 20, 2002, plaintiff and Dana’s sister, Lori Schwartz (who is not a party to this appeal), filed this wrongful death action against defendants.  Their operative second amended complaint was filed on December 20, 2002.  Plaintiff alleged that Dana died as the result of defendants’ medical malpractice.  Plaintiff sought compensatory damages, including compensation for the loss of love, companionship, comfort, affection, solace and moral support, that she suffered as a result of Dana’s death.  Plaintiff also sought compensation for burial and funeral expenses, as well as the loss of Dana’s income and future earnings.
Defendants demurred to plaintiff’s causes of action.  Relying on Code of Civil Procedure section 377.60 (section 377.60 or the wrongful death statute) and Family Code section 297, defendants asserted that plaintiff lacked standing to sue them for wrongful death, in that she and Dana had failed to file a Declaration of Domestic Partnership with the Secretary of State.
Plaintiff opposed the demurrers.  Although she acknowledged that she and Dana had not fulfilled the registration requirement necessary to establish a domestic partnership, she argued that they had fulfilled the statutory intent and underlying purpose of domestic partnership registration despite the lack of registration.
The trial court, believing it had no discretion in this matter, sustained the demurrers without leave to amend based on the failure to file a Declaration of Domestic Partnership with the Secretary of State.  On May 7, 2003, the trial court dismissed all of plaintiff’s causes of action with prejudice.  This appeal followed.

CONTENTIONS

The trial court’s decision to sustain defendants’ demurrers without leave to amend was based upon the 2002 version of the wrongful death statute.  Plaintiff contends that under the most reasonable construction of that statute and the domestic partnership law, she need not allege that she and Dana registered their domestic partnership with the Secretary of State in order to establish standing.  Plaintiff further contends that a registration requirement would run afoul of the state and federal equal protection clauses and that, apart from whether she and Dana were domestic partners under the 2002 wrongful death statute, she nevertheless was entitled to bring this lawsuit under the equal protection and privacy guarantees of the California Constitution and under the equal protection and due process provisions of the United States Constitution.  We conclude that registration is a prerequisite for standing under the 2002 version of the wrongful death statute.  We further conclude, however, that the 2005 version of the wrongful death statute affords plaintiff standing to sue.  We therefore need not and do not address plaintiff’s remaining constitutional contentions regarding the 2002 wrongful death statute.
With respect to the 2005 wrongful death statute, Assembly Bill 2580 (AB 2580), defendants  contend that the Legislature amended the wrongful death statute for the sole purpose of changing the results in three cases presently on appeal.  Defendants concede that the statute expressly provides that it is to have retroactive effect but contend that various constitutional provisions prevent the statute’s retroactive application in this case.  Defendants further contend that even if there is no constitutional impediment to the statute’s retroactive application, AB 2580 cannot be enforced because it violates Proposition 22, an initiative measure approved by California voters during the March 2000 election.  For the reasons that follow, there is no merit to these contentions.

DISCUSSION

I.OVERVIEW OF PERTINENT STATUTORY PROVISIONS
In order to place the issues in this case into perspective, an understanding f the evolution of the wrongful death statute in relationship to California domestic partnership law is required.  In 1999, the Legislature passed Assembly Bill 26 (AB 26), which became effective on January 1, 2000.  Among other things, AB 26 added Division 2.5, entitled “Domestic Partner Registration” (commencing with section 297), to the Family Code.  (Stats. 1999, ch. 588, § 2.)  This division set forth the definitions of domestic partners and domestic partnership, the procedural steps to be taken to register or to terminate a domestic partnership, the legal effect of registering a domestic partnership, and preemption provisions.
As originally enacted, Family Code section 299.5 provided that “[r]egistration as a domestic partner under this division shall not be evidence of, or establish, any rights existing under law other than those expressly provided to domestic partners in this division and Section 1261 of the Health and Safety Code.”  AB 26 “require[d] a health facility to allow a patient’s domestic partner and other specific persons to visit a patient, except under specified conditions” and “authorize[d] state and local employers to offer health care coverage and other benefits to domestic partners.”  (Legislative Counsel’s Digest, AB 26; 9 West’s California Legislative Service (1999), ch. 588, p. 3373.)  The new legislation conferred no other rights.
When Dana died in August 2001, California’s wrongful death statute did not confer standing on a surviving domestic partner.  Legislation passed in 2001, shortly after Dana’s death, changed this.  On October 14, 2001, Assembly Bill 25 (AB 25) (Stats. 2001, ch. 893) was enacted.  Effective January 1, 2002, AB 25 amended subdivision (a) of section 377.60 to add the decedent’s surviving “domestic partner” to the list of individuals entitled to sue for wrongful death.
AB 25 also added subdivision (f) to section 377.60, which specified that for purposes of the wrongful death statute, the term “‘domestic partners’ has the meaning provided in Section 297 of the Family Code.”   (Stats 2001, ch. 893, § 2.)  Subdivision (d) of section 377.60, which prior to the 2002 amendment provided that the wrongful death statute “applies to any cause of action arising on or after January 1, 1993,” was re-enacted without change, thereby reflecting the Legislature’s clear intent that the 2002 amendment have retroactive application.
In 2003, the Legislature enacted Assembly Bill 205 (AB 205), the California Domestic Partner Rights and Responsibilities Act of 2003.  (Stats. 2003, ch. 421, § 2.)  Among other things, AB 205 amended Family Code section 297’s definition of domestic partnership.  (Stats. 2003, ch. 421, § 3.)
AB 205 also significantly expanded the rights and protections provided to registered domestic partners.  Specifically, it “extend[ed] the rights and duties of marriage to persons registered as domestic partners on and after January 1, 2005.”  (Leg. Counsel’s Digest AB 205; 8 West’s Cal. Legislative Service (2003) ch. 421, p. 2587.) AB 205 added section 297.5 to the Family Code.  It provided in part:  “(a) Registered domestic partners shall have the same rights, protections, and benefits, and shall be subject to the same responsibilities, obligations, and duties under law, whether they derive from statutes, administrative regulations, court rules, government policies, common law, or any other provisions or sources of law, as are granted to and imposed upon spouses.”  Family Code section 297.5 (Stats. 2003, ch. 421, § 4), and the amendment to Family Code section 297 (Stats. 2003, ch. 421, § 3), became operative on January 1, 2005.  (Stats. 2003, ch. 421, § 14.)
In 2004, while this appeal was pending but after the parties had fully briefed this case, AB 2580 was enacted into law (Stats. 2004, ch. 947, § 1).  The Legislative Counsel’s Digest to AB 2580, as amended in the Senate August 16, 2004, states, in part, that “[e]xisting law provides that a cause of action for the wrongful death of a person may be asserted by his or her domestic partner, as defined.  []  Under certain circumstances, this bill would allow a cause of action for wrongful death to proceed pursuant to the above although a Declaration of Domestic Partnership was not filed with the Secretary of State, if other specified requirements are met.”  (Italics omitted.)
AB 2580 amended subdivision (f) of the wrongful death statute.  Effective January 1, 2005, section 377.60, subdivision (f), provides:  “(1) For the purpose of this section, ‘domestic partner’ means a person who, at the time of the decedent’s death, was the domestic partner of the decedent in a registered domestic partnership established in accordance with subdivision (b) of Section 297 of the Family Code.
“(2) Notwithstanding paragraph (1), for a death occurring prior to January 1, 2002, a person may maintain a cause of action pursuant to this section as a domestic partner of the decedent by establishing the factors listed in paragraphs (1) to (6), inclusive, of subdivision (b) of Section 297 of the Family Code, as it read pursuant to Section 3 of Chapter 893 of the Statutes of 2001, prior to its becoming inoperative on January 1, 2005.
“(3) The amendments made to this subdivision during the 2003-2004 Regular Session of the Legislature are not intended to revive any cause of action that has been fully and finally adjudicated by the courts, or that has been settled, or as to which the applicable limitations period has run.”  (Italics added.)

II.UNDER THE 2002 VERSION OF THE WRONGFUL DEATH STATUTE, ONLY REGISTERED SURVIVING DOMESTIC PARTNERS HAVE STANDING TO SUE FOR WRONGFUL DEATH
We reject plaintiff’s contention that under the 2002 wrongful death statute, registration of her partnership with Dana was not a prerequisite to her standing to sue for Dana’s wrongful death.  In Holguin v. Flores (2004) 122 Cal.App.4th 428, Division Seven of this Court held that registration as a domestic partnership was required in order for the surviving domestic partner to sue for the wrongful death of the deceased partner.  The court reached this conclusion after an extensive review of the 2002 wrongful death statute, relevant provisions of the domestic partnership law and legislative history underlying those provisions.  (Id. at pp. 434-437.)
We agree with Holguin and adopt its reasoning.  Accordingly, we hold that a surviving domestic partner can sue for wrongful death under the 2002 version of the wrongful death statute only if at the time of the decedent’s death the partnership had been registered with the Secretary of State.  Inasmuch as plaintiff and Dana were not registered domestic partners at the time of Dana’s death, and plaintiff could not amend her complaint to allege registration, the trial court correctly determined that plaintiff lacked standing to sue for Dana’s wrongful death under the 2002 version of the wrongful death statute.  We nevertheless must reverse the judgment because a subsequent amendment to the wrongful death statute, which amendment applies retroactively, confers on plaintiff the requisite standing even in the absence of partnership registration.  We therefore need not and do not reach the merits of plaintiff’s remaining contentions with respect to the 2002 wrongful death statute.  We now turn to defendants’ challenges to the 2005 wrongful death statute.

III.THE LEGISLATURE PASSED AB 2580 FOR THE PURPOSE OF CLARIFYING PREVIOUS LEGISLATION
AB 2580 was a clean-up bill designed to clarify through technical changes that various provisions of the California Domestic Partner Rights and Responsibilities Act (Fam. Code, § 297 et seq.; Stats. 2003, ch. 421; AB 205) apply to state-registered domestic partners.  (Assem. Com. on Judiciary, Analysis of Assem. Bill 2580 (2003-2004 Reg. Sess.) as introduced Feb. 20, 2004, p. 1.)  This particular bill was sparked by inquiries as to whether AB 205 applied to domestic partners registered at one of the 59 local jurisdictions.  (Ibid.)
The August 10, 2004 senate floor amendments to AB 2580 sought to “clarify application of existing law to wrongful death actions brought by domestic partners . Among the provisions amended by AB 25 was Section 377.60 of the Civil Code [sic], to allow domestic partners to assert wrongful death claims in the same manner as spouses.  Apparently courts have interpreted the amendment made by AB 25 to Section 377.60 of the Civil Code [ ], as applied to deaths prior to its effective date of January 1, 2002, in different and conflicting ways.  These amendments to AB 2580 clarify the application of the AB 25 amendments to those wrongful death actions.  The amendments will not affect actions that have been adjudged or settled or where the statute of limitations has run.”  (Sen. Rules Com., Off. of Sen. Floor Analyses, 3d reading analysis of Assem. Bill No. 2580 (2003-2004 Reg. Sess.) as amended Aug. 10, 2004, pp. 1-2.)
Contained in the legislative history materials supplied by plaintiff is a Senate Committee on Judiciary “Background Information Request.”  Following as “background material in explanation of the bill,” is a document entitled “Explanation of Proposed Amendment to Wrongful Death Statute (Code of Civil Procedure Section 377.60) for Possible Inclusion in AB 2580 (2004) (Goldberg).”
This document references AB 25, which amended the wrongful death statute effective January 1, 2002 by adding surviving domestic partners to the list of individuals who had standing to bring a wrongful death cause of action.  Of particular interest is Part C of the document entitled, “The Need for Clarification With Respect to Suits for Wrongful Deaths Occurring Prior to January 1, 2002.”  It explains that “[u]nfortunately, some of the plaintiffs for whom the Legislature contemplated that AB 25 would authorize recovery—that is, plaintiffs bringing wrongful death actions for pre-2002 deaths—have found themselves in a legal ‘Catch-22’ that the Legislature did not contemplate.  During the lifetimes of their now-deceased partners, the plaintiffs that the Legislature expected to benefit from the retroactive availability of the wrongful death cause of action had no reason to expect that registration would entitle them to the protections of the wrongful death statute.  Indeed, for the duration of years 2000 and 2001, Family Code section 299.5 expressly prohibited courts from considering registration as evidence of the right to bring any cause of action.”
Part C further explains that lawsuits filed under AB 25 with regard to pre-2002 deaths have resulted in incongruent holdings, necessitating clarification by the Legislature of the standing requirements.  Such clarification effectively would conserve judicial resources in ongoing litigation by obviating the need for the Legislature to decide complex constitutional issues relating to same-sex partners’ previous inability to sue for wrongful death.  Claims barred by the statute of limitations would not be revived.  In addition, legislative clarification would “confirm[] that these surviving partners have a fair and rational legal remedy, as was intended by AB 25.”
The Legislature’s decision to amend the wrongful death statute therefore was fueled by its recognition that AB 25, as enacted, did not fully achieve its desired result—retroactive enjoyment of the benefit of the wrongful death statute by all surviving domestic partners for deaths occurring prior to January 1, 2002.  References in the legislative materials to ongoing litigation and the disparate results reached therein served only to highlight the need for amendment of the wrongful death statute.  Contrary to defendants’ assertion, such references do not evince an intent on the part of the Legislature to usurp the function of the judiciary.

IV.DEFENDANTS HAVE FAILED TO DEMONSTRATE THAT THERE IS A CONSTITUTIONAL IMPEDIMENT TO THE RETROACTIVE APPLICATION OF AB 2580
Defendants concede that the wrongful death statute as amended by AB 2580 provides that it is to apply retroactively.  Defendants argue, however, that “it would be unconstitutional to apply AB 2580 retroactively here because: (1) it violates Dr. Miles’ due process rights by substantively changing the law regarding wrongful death tort liability, thereby upsetting Dr. Miles’ vested rights; (2) it violates the separation of powers by directing courts how to rule on pending appeals; (3) it constitutes an unconstitutional bill of attainder by singling out for punishment a small discreet group of defendants and [violates the prohibition against ex post facto laws; and] (4) it violates Dr. Miles’ equal protection rights by treating her differently from other similarly situated doctors who will not be liable in wrongful death actions brought by surviving non-registered domestic partners.”  As we now explain, each of defendants’ constitutional challenges lacks merit.  We discuss each in turn.

A.Due Process
Defendants contend that it would be unconstitutional to apply AB 2580’s amendment of the wrongful death statute retroactively.  In defendants’ view, AB 2580 is a legislative act that deprives them of a vested right without due process of law.  We disagree.
Our state’s high court has long held that the retroactive application of a statute may be unconstitutional if it deprives an individual of a vested right without due process of law.  (In re Marriage of Buol (1985) 39 Cal.3d 751, 756, 758.)  “A right is ‘vested’ when it is ‘“already possessed”’ or ‘“legitimately acquired.”’”  (Standard Oil Co. v. Feldstein (1980) 105 Cal.App.3d 590, 605, quoting Harlow v. Carleson (1976) 16 Cal.3d 731, 735.)
The right to sue for wrongful death by a person on whom the Legislature has conferred such right vests on the decedent’s death.  Once that right has vested, the Legislature cannot impair it.  (Wexler v. City of Los Angeles (1952) 110 Cal.App.2d 740, 747.)  Defendants assert that “[s]imple fairness dictates that the reverse must also be true — where a potential wrongful death defendant is protected by the law from any liability at the time of decedent’s death the Legislature should be barred from retroactively imposing liability where none existed before.”  We reject this argument.
Defendants do not cite to any California or federal case law that compels the conclusion that a person who wrongfully or negligently causes another’s death has a right, vested or otherwise, to have the class of potential plaintiffs frozen as of the time of death.  Expansion of the class of plaintiffs who can sue for wrongful death does not change the legal definition of negligence, the standard by which liability is assessed, or the character of defendants’ acts or omissions.  It simply enlarges the class of plaintiffs to whom defendants may be liable for their purported negligence.
Defendants’ reliance on Theodosis v. Keeshin Motor Express Co. (1950) 341 Ill.App. 8 [92 N.E.2d 794] is misplaced.  In Theodosis, the question before the Illinois appellate court was whether the Injuries Act of 1947, which increased the limit of recovery from $10,000 to $15,000, should be construed to apply retroactively.  (At p. 795.)  The Illinois court concluded that it could not be applied retroactively based on case law and a specific statute prohibiting retroactive application of statutes.  (Id. at pp. 795-802.)  Theodosis did not bar retroactive application of the Injuries Act of 1947 on due process grounds.  Theodosis is of no aid to defendants and, in any event, we are not bound by the decisions of courts of other states.  We conclude that defendants have not demonstrated a due process violation.