We have before us an appeal involving legal *464principles generally referred to as "estoppel by judgment,” "collateral estoppel,” "estoppel by verdict,” or "res judicata.” See generally Sumner v. Sumner, 186 Ga. 390 (197 SE 833); Smith v. Wood, 115 Ga. App. 265 (154 SE2d 646). In a prior diversity of citizenship case brought in the United States District Court for the Middle District of Georgia, Otis Porterfield and his wife sought recovery from Philco Distributors, Inc. based solely upon the alleged negligence of Philco’s servant, Jeffrey Gilmer, in causing a collision between Philco’s automobile being operated by Gilmer and the Porterfield pickup truck being operated by Mr. Porterfield in which his wife was a passenger.1 In that case Philco accepted responsibility for any negligence of Gilmer under the doctrine of respondeat superior; plaintiffs’ proffer of evidence as to Gilmer’s admissions of negligence or declarations against interest at the scene was ruled inadmissible as against Philco, the master and sole defendant; the jury was charged the doctrine of comparative negligence vis-a-vis Gilmer and Mr. Porterfield; the jury returned a verdict in favor of Mrs. Porterfield on her claim but, apparently as a result of the comparative negligence charge, in favor of Philco on Mr. Porterfield’s claim; and the judgment became final.
Mr. Porterfield then instituted the present action against Gilmer based upon the same acts of negligence involved in the prior case against Gilmer’s master, Philco, and was confronted in Gilmer’s first defense with a plea of "res judicata and/or estoppel by judgment and/ or the law of the case and/or the fact that all of these matters were either previously litigated or could have been litigated previously.” Plaintiff Porterfield and defendant Gilmer both moved for summary judgment as to Gilmer’s first defense; the trial court granted Gilmer’s motion and denied that of Porterfield; and Porterfield complains of both rulings, having obtained a certificate *465of immediate review as to the denial of his motion. Porterfield contends, inter alia, that the trial court’s ruling was erroneous since Gilmer’s admissions of negligence or declarations against interest at the scene, ruled inadmissible as against Philco on the prior trial, would be admissible against Gilmer in the instant suit, thus affecting and adding to the quantum and quality of proof on the issue of Gilmer’s negligence. Held:
We reverse both rulings. We held in Davis v. Bryant, 117 Ga. App. 811 (162 SE2d 249), that the relationship of master and servant does not ipso facto constitute privity for purposes of res judicata or estoppel by judgment. " [T]he rule that where the liability of the master to a third person is purely derivative and dependent entirely upon the principle of respondeat superior, a judgment on the merits in favor of the agent or servant is res judicata in favor of the principal or master, though he was a party to the action, 'is an exemplification of the broader rule by which one whose liability is wholly derivative may claim the benefit of a judgment in favor of the person from whom his liability is derived.’ ” Davis v. Bryant, 117 Ga. App. 811, 812-813, supra, quoting from Roadway Express, Inc. v. McBroom, 61 Ga. App. 223 (6 SE2d 460). The master, sued for the negligence of his servant under the doctrine of respondeat superior, may claim the benefit of a prior judgment in favor of the servant since all evidence bearing on the issue of the servant’s negligence would have been admissible in the suit against the servant, thus fully and finally adjudicating that issue. However, there is no rule of law that all evidence admissible against the servant himself is ipso facto admissible against the master, and it is the quantum and quality of evidence which determines the outcome of the substantive issue of the servant’s negligence. Hence the ruling in Hunter v. Embree, 122 Ga. App. 576 (178 SE2d 221), which is dispositive of this appeal: "The liability of a [master] to a third person is purely derivative and dependent upon the doctrine of respondeat superior and a judgment on the merits in favor of the agent or servant is res judicata in favor of the [master], though he was not a party to the action. Roadway Express, Inc. v. McBroom, 61 Ga. App. 223, supra; Giles v. Smith, 80 Ga. App. 540 *466(56 SE2d 860). In the reverse situation (which we have here) where the [master] received the judgment in his favor, the [servant] cannot claim the benefit of the prior judgment as a bar to an action against him individually, as his liability to a third person is not derivative.”
It is suggested that we overrule Hunter v. Embree, supra, and that the requirement of mutuality of estoppel be abandoned. The general rule is "that the operation of the doctrine of res judicata [or estoppel by judgment] must be mutual, and that one of the essential elements of the doctrine is that both the litigants must be alike concluded by the judgment, or it binds neither. Under this rule, if a judgment cannot be effective as res judicata against a person, he may not avail himself of the adjudication and contend that it is available to him as res judicata against others. ”46 AmJur2d 673, Judgments, § 521. (Emphasis supplied.) In the instant case, the prior federal court judgment is not effective as res judicata or as estoppel by judgment against Gilmer, thus leaving him free to claim or counterclaim against Porterfield. Davis v. Bryant, 117 Ga. App. 811, supra. Consequently, unless the requirement of mutuality be abandoned, Gilmer may not avail himself of the judgment and contend that it is available to him as a bar against Porterfield.
"It is a general universal rule that estoppels must be mutual. Strangers can neither take advantage of, nor be bound by an estoppel.” Luke v. Hill, 137 Ga. 159, 161 (73 SE 345). "And that which is not an estoppel, to the party insisting on it as an estoppel, cannot be an estoppel to the other party. Estoppel, to be good, must be 'reciprocal.’ ” Gaither v. Gaither, 23 Ga. 521, 528 (3). "Estoppels by judgment, like estoppels in pais, must be mutual.” Dodd v. Mayfield, 99 Ga. 319, 320 (25 SE 698). "Estoppels are not favored at law and in no case can the doctrine be invoked save where the estoppel is mutual. Harris v. Amoskeag Lumber Co., 101 Ga. 641, 643 (29 SE 302); Dodd v. Mayfield, 99 Ga. 319, 320 (25 SE 698); Luke v. Hill, 137 Ga. 159 (1) (73 SE 345, 38 LRA(NS) 559); Whitman v. Bolling, 47 Ga. 125, 133.” Tarver v. Jones, 34 Ga. App. 716, 717 (2) (131 SE 102)."'There is one general rule, which is applicable alike to estoppel by record, by deed, and to equitable estoppel or estoppel in *467pais: that is, that estoppels must be mutual. Strangers can neither take advantage of, nor be bound by an estoppel; its binding effect is between the immediate parties, their privies in blood, in law and by estate.’ ” Howard v. Perkins, 229 Ga. 279, 281 (191 SE2d 46).
Argued April 2, 1974 Decided April 17, 1974 Rehearing denied July 19, 1974 William O. Carter, for appellant. Long, Weinberg, Ansley & Wheeler, Sidney F. Wheeler, for appellee.In view of the Supreme Court’s adherence to the mutuality rule, we are not free to abandon it in this court. Since Gilmer is not bound by the prior judgment, the mutuality rule precludes him from taking advantage of it.
Order granting summary judgment to Gilmer is reversed; order denying summary judgment to Porterfield as to Gilmer’s first defense is reversed with direction to strike the defense.
Bell, C. J., Pannell, P. J., Deen and Quillian, JJ., concur. Eberhardt, P. J., Clark and Stolz, JJ., dissent.Gilmer was not joined as a party defendant, apparently because of a lack of diversity of citizenship, the Porterfields and Gilmer all being Georgia residents.