Defendant asserts that because of these payments, the insurance company is a real party in interest and should be joined as a party plaintiff.
The 'real party in interest' within the meaning of Rule 17(a) is the party who, under the applicable substantive law, has a legal right to enforce the claim. Capo v. C-O Two Fire Equipment Co., D.C.D.N.J.1950, 93 F.Supp. 4, 6; Du Roure v. Alvord, D.C.S.D.N.Y.1954, 120 F.Supp. 166, 168. The law of New York is the substantive law applicable
and, under that law, an insurance company which pays part of a loss incurred by its insured becomes joint owner with the insured of the cause of action. Moore v. Taylor, 1916, 175 App.Div. 37, 161 N.Y.S. 480, 481-482. See Porter v. Lane Const. Corporation, 1925, 212 App.Div. 528, 209 N.Y.S. 54, 57, affirmed 1926, 244 N.Y. 523, 155 N.E. 881. Hence, Security Mutual Insurance Co. has the substantive right under New York law to assert a claim for the amount it paid in settlement of the third party claims.
Once it has been established that under the applicable substantive law the party sought to be joined has the right to maintain the action, whether or not such a party should be joined under Rule 17(a) depends on federal procedural standards.
This is a case of partial subrogation
and, in such cases, both the insured and the insurer are real parties in interest within the meaning of F.R.Civ.P. rule 17(a). United States v. Aetna Casualty & Surety Co., 1949, 338 U.S. 366, 381, 70 S. Ct. 207, 94 L. Ed. 171. Although an action can be instituted by either party,
the other should be joined upon timely motion of the defendant. St. Paul Fire & Marine Ins. Co. v. Peoples Natural Gas Co., D.C.W.D.Pa.1958, 166 F.Supp. 11, 12. This motion is timely
and there is no reason to deny defendant its right to join Security Mutual Insurance Company of New York as a party plaintiff.
The order attached to defendant's motion (Document No. 16), making The Security Mutual Insurance Company of New York a party plaintiff, will be signed. The briefs of counsel have been filed as Nos. 18 and 19 in the Clerk's file.