This is a  NJ case of legal malpractice, but it touches on "judicial estoppel"  "mutually exclusive positions" the difference between "successive and alternative tortfeasors" and what is in New York called the "effectively compelled" rule.  In New York a legal malpractice plaintiff must prove that a settlement was effectively compelled by the attorney’s mistakes, and was not simply a strategic position.

Here in this NJ case:

"While plaintiff in the first action could have joined the defendants in this case, he did not do so, nor did he put the defendants in the first action on notice of the Arnold defendants’ potential liability to the plaintiff. It would have been perfectly acceptable for plaintiff in the first action to have advanced alternative theories of liability. See City of Jersey City v. Hague, 18 N.J. 584, 603 (1955). Rather than doing so, however, plaintiff proceeded with his first action against the sellers, realtors, home inspector and other defendants and settled same.

Plaintiff pleaded the defendants in both of these suits as alternative tortfeasors rather than joint or successive tortfeasors. Joint tortfeasors are "two or more persons jointly or severally liable in tort for the same injury to persons or property, whether or not judgment is recovered against all or some of them," N.J.S.A. 2A:53A-1. The test for joint tortfeasor liability is whether defendants had "common liability at the time of the accrual of plaintiff’s cause of action." Markey v. Skog, 129 N.J. Super. 192, 200 (Law Div. 1974); and see Cherry Hill Manor Assoc. v. Faugno, 192 N.J. 64, 76 (2004). A successive tortfeasor is one whose liability succeeds that of an initial tortfeasor; for example, a doctor who negligently treats a party injured at an accident caused by an initial tortfeasor. See, e.g. Ciluffo v. Middlesex General Hosp., 146 N.J. Super. 476, 484 (App. Div. 1977), (holding that when a plaintiff settles with an initial tortfeasor for less than the full amount of her damages, she may proceed against the successive tortfeasor for the remainder of her damages).

In this case, the Arnolds are alternative tortfeasors, meaning that once plaintiff recovered from the sellers, he can not recover from the Arnolds. This is because the alternative theories advanced in each of the law suits are based on mutually exclusive inconsistent factual allegations. In going against defendants in the first action, plaintiff alleges that he was not appropriately informed of the serious structural defects in the home. In pursuing his cause against the Arnolds he states he was advised of the serious defects, directed his attorneys to terminate the contract or negotiate a reasonable price reduction to accommodate the repairs and that the attorneys negligently failed to do so. These are two mutually exclusive factually-based theories of liability against two groups of defendants. By settling with the sellers and the other defendants in the first action, plaintiff is estopped from proceeding against the attorneys. This is because in this factual setting the inescapable fact is that the plaintiff could not have recovered against both groups of defendants. See Norcia v. Liberty Mutual Insurance Co., 297 N.J. Super. 563, 570 (Law Div. 1966), aff’d o.b., 308 N.J. Super. 194 (App. Div. 1998), certif. denied, 154 N.J. 608 (1998). If plaintiff had joined all defendants together in the first action, an award against both the attorney defendants and defendants in the first suit, would have been impossible under the mutual exclusive alternative factual theories advanced.

We believe though, that the trial judge mistakenly used the phrase "judicial estoppel" as the rationale for her ruling. Judicial estoppel binds a party only to a position that it successfully asserted in the same or prior proceeding. Kimball Inter. v. Northfield Metal, 334 N.J. Super. 596, 606 (App. Div. 2000). Plaintiff by settling did not successfully advance for judicial acceptance his position. Hence, the doctrine of judicial estoppel does not apply.

That judicial estoppel is not applicable does not mean, however, that plaintiff may advance against defendants in a later suit a position that is mutually exclusive and factually inconsistent with a position advanced against other defendants in an earlier suit. Plaintiff’s choice to institute the first action without joining his alternative tortfeasors as co-defendants, and his election to settle the case against the seller defendants and receive those settlement funds can be viewed as confirming plaintiff’s assertion that the sellers failed to adequately disclose the conditions of the property. See, e.g., Norcia v. Liberty Mutual supra, at 569.

While we recognize that a party may advance an alternative and inconsistent pleading under Rule 4:5-6, we hold that a plaintiff is estopped from pursuing a successive action against a tortfeasor where: (1) plaintiff earlier settled a suit against other tortfeasors for the same damages; (2) the preceding suit was based upon a mutually exclusive inconsistent position with the successive action; (3) all of the alleged tortfeasors in both suits are alleged to be liable to plaintiff for the same damages but on the basis of a different standard of care or duty; and (4) plaintiff failed to provide the required Rule 4:5-1(b)(2) notice in the preceding suit. Such estoppel is in accord with fairness and public policy. See, e.g., Puder, supra, 183 N.J. Super. 428. Estopping plaintiff from bringing this action is consistent with our court’s policy of favoring settlements, promoting judicial economy, promoting party fairness, encouraging comprehensive and conclusive litigation determinations, avoiding fragmented litigation, preserving the integrity of the judicial process, and insuring candor and fair dealing with the courts.

The initial defendants, if informed of potential co-defendants, could have joined them and may have differently evaluated their litigation and settlement strategies. The attorney defendants, while they might file a third-party complaint against the initial defendants for indemnity or contribution in this case, would be prejudiced by having to advance plaintiff’s initial factual position without the cooperation of plaintiff – a difficult task where plaintiff’s allegation was he was defrauded. "