http://www.pacourts.us/OpPosting/Cwealth/out/1912CD10_8-26-11.pdf
Under the doctrine of res judicata, or claim preclusion, an action is barred because it is grounded, either in whole or in part, upon a claim which was the subject of a prior adjudication by a court of competent jurisdiction. R/S Financial Corp. v. Kovalchick, 552 Pa. 584, 588, 716 A.2d 1228, 1230 (1998).
Therefore, if a court renders a final judgment on the merits, res judicata will preclude any future suit between the parties on the same cause of action, or concerning any claims which could have been litigated during the first proceeding. Id. See also Callowhill Center Associates, LLC v. Zoning Board of Adjustment, City of Philadelphia, 2 A.3d 802, 809 (Pa. Cmwlth. 2010).
In order for the doctrine of res judicata to apply four conditions must concur:
(1) identity of the thing sued upon or for;
(2) identity of the cause of action;
(3) identity of the persons and parties to the action; and
(4) identity of the quality or capacity of the parties.
Stevenson v. Silverman, 417 Pa. 187, 190, 208 A.2d 786, 787-788 (1965); Swift v. Radnor Township, 983 A.2d 227, 232 (Pa. Cmwlth. 2009).
Generally, a cause of action will be considered identical when the subject matter and the ultimate issues are the same in both proceedings. Swift, 983 A.2d at 232.
Finally, it is well-settled that res judicata will not be "defeated by minor differences of form, parties, or allegations, when these are contrived only to obscure the real purpose, -- a second trial on the same cause between the same parties." Stevenson, 417 Pa. at 192, 208 A.2d at 788 (quoting Hochman v. Mortgage Finance Corporation of Pennsylvania, 289 Pa. 260, 263, 137 A. 252, 253 (1927)).
Res judicata bars all causes of action that were either raised or could have been raised during a prior proceeding. R/S Financial Corp., 552 Pa. at 588, 716 A.2d at 1230 (emphasis added).
