This appeal involves the respective rights of an insured owner and his collision coverage insurer to maintain an action against a tort-feasor defendant based upon damage to the insured’s automobile. In this action the plaintiff, insured owner, in substance alleged: that while his automobile was being driven by a bailee the defendant tort-feasor negligently caused his pickup truck to collide with that automobile damaging the same in the amount of $1928.15; that by reason of loss of use he had expense of $1450.00; and he prayed judgment for a total of $3378.15. The defendant moved to dismiss the petition alleging the plaintiff had assigned his cause of action to his insur *599 er and therefore the plaintiff was not the real party in interest. The motion was supported by plaintiff’s admission that he did execute an instrument entitled “Proof of Loss” which recited the occurrence, actual damage of $1449.15, a deductible of $50.00, and that for $1399.15 the insured released the insurer and acknowledged the receipt of that amount in full satisfaction and settlement of said loss. The instrument in a separate paragraph provided: “The insured hereby assigns, transfers, and sets over to the Insurer any and all claims or causes of action of whatsoever kind and nature which the Insured now has, or may hereafter have, to recover against any person or persons as the result of said occurrence and loss above described, to the extent of the payment above made . . .” (emphasis added) The insured further agreed “the Insurer may enforce the same” for the benefit of the insurer in its own name or in the name of the insured. The motion to dismiss was sustained and the plaintiff appeals. His point relied on is that the trial court erred for the reason the proof of loss was not an assignment of the plaintiff’s entire claim for damages.
Upon payment of all or part of the insured’s damages, the interest of a collision insurer in the insured’s cause of action against a tort-feasor is most often established by subrogation or assignment. While subrogation is frequently equated with assignment and has been referred to as assignment by operation of law, the two methods are, at least for some purposes, distinct.
1
Subrogation may arise by operation of law or by agreement, the distinction and relationship between the two not being pertinent to this decision. Assignment results from agreement. When an insurer acquires such an interest in the cause of action a determination of which party or parties may, or must, prosecute that cause of action has been found to be dependent upon many factors, including the extent of the insurer’s interest, how that interest was derived, and the interrelationship between the real party in interest statute and the rule against splitting a cause of action. It is not unexpected that in making such determination the state and federal courts have reached differing conclusions. See Annot., Insurer-Parties-Partial Loss,
In the Missouri courts it has been established that such a determination hinges upon whether the interest of the insurer is derived by subrogation or assignment of the cause of action.
2
If the interest of the insurer is derived by subrogation, the action must be brought by, or at least in the name of, the insured.
State Farm Mutual Automobile Ins. Co. v. Jessee,
However, the instrument in
Hoor-man
serves to point up the essential nature of the instrument in this case. In
Hoorman
*600
the instrument read the insurer “ ‘is hereby subrogated to all claims and rights of action . to the amounts so paid and the undersigned
assigns
and sets over to the said company
all such claims
with the right to prosecute the said action or actions in the name of the assignor.’”
Hoorman v. White,
supra,
While no cases have been cited to this court, and undoubtedly none were cited to the trial court, instruments such as the one in question have consistently been construed to constitute partial assignments of the cause of action.
State ex rel. Home Service Oil Company v. Hess,
However, lest the import of this opinion might be misconstrued, the result reached need not be based upon those cases. The rationale that a partial assignment of an assignable cause of action conveys nothing but an equitable interest is not consistent with current trends.
4
The same is true of the uncited doctrine, said to be unique to this state, “in Missouri, contrary to the prevailing rule, no suit may be maintained against a debtor on a partial assignment without his consent either at law or in equity.”
Howard Undertaking Co. v. Fidelity Life Ass'n.,
The more recent doctrine has been summarized:
Under modern practice, where procedural distinctions between law and equity have been abolished, and legal and equitable remedies are secured by the same form of action, it is generally conceded that if part of an obligation or demand has been assigned, the assignee can maintain an action to recover his share by joining the assignor as plaintiff, or, if he will not join, by making him a defendant, so that the whole controversy may be settled in one suit. 6 Am.Jur.2d Assignments § 132, pp. 313-314.
This doctrine was recognized by this court in saying:
It could assign its interest in the contract to as many different parties as it saw fit and those parties could hold as tenants in common or as joint tenants. Such action on the part of the corporation, acting without the assent of defendants, could not, however, split the cause of action and authorize a multitude of suits where only one right of action had previously existed. (cites omitted)
*601 It is our conclusion that plaintiff could not maintain this action without joining the other assignees of the contract as plaintiffs with him, or, if they would not join as plaintiffs, he should have made them defendants as the statute cited provides may be done. Hoppock v. Gaines,284 S.W. 191 , 192-193 (Mo.App.1926).
A typical expression of the recent doctrine is found in a California case.
At common law, a partial assignee had no legal standing to sue; the underlying rationale was that the original creditor could not split his cause of action and sue the debtor in two actions, and he could not bring about the same result by assigning part of the claim to another and subjecting the debtor to two suits by different plaintiffs. Enforcement of a partial assignment of a claim was permitted in equity, however, by the process of requiring joinder of all interested parties; i. e., the assignor and all partial assignees ‘under the codes, which have merged legal and equitable actions and adopted the equity procedure of joinder, there is no longer any procedural obstacle to enforcement of the partial assignment. The plaintiff partial assignee may sue by joining the partial assignor . . . .’ Cain v. State Farm Mutual Automobile Insurance Co.,47 Cal.App.3d 783 , 794-795,121 Cal.Rptr. 200 , 207 (1975). 5
However, even following the more recent doctrine, the dismissal cannot be sustained. Assuming the legal title to the cause of action is vested in the insured and insurer, the plaintiff insured is a real party in interest and his failure to join the insurer, as plaintiff or defendant, constitutes a non-joinder. While V.A.M.R. Civil Rule 52.06 does not prohibit dismissal for nonjoinder, “[w]hen the issue is whether the suit should proceed or be dismissed for failure to join a person as a party (nonjoinder), Rule 52.04 is the procedural rule which controls the matter.”
Kingsley v. Burack,
Notes
.
Kroeker v. State Farm Mutual Automobile ins. Co.,
. The cases are collected in
Alsup v. Green,
.
Truitt v. National Life & Accident Ins. Co.,
. In speaking of the reasoning in
Subscribers at Casualty Reciprocal Exchange v. Kansas City Public Service Company,
. Also see
Blake v. Weiden,
