Pleadings - Law. Bulut v Carter
In Bulut v Carter (Ont CA, 2014) the Court of Appeal considered the extent to which legal issues had to be set out in pleadings in order to be arguable by the party advancing them. Essentially the court held that if the material facts underpinning the legal principle that the party wished to advance were set out in the pleadings, even though the legal doctrine was not expressly pled, then the party may advance that legal argument:
 Fairness dictates that lawsuits be decided within the boundaries of the pleadings. A party has the right to know the case it has to meet and to have the opportunity to meet it: Rodaro v. Royal Bank of Canada 2002 CanLII 41834 (ON CA), (2002), 59 O.R. (3d) 74 (C.A.).. Holmes v. Hatch Ltd.
 The defence of non est factum was not expressly identified in the respondents’ amended statement of defence and counterclaim. However, in their pleading, the respondents did allege that they did not understand the nature of the document they signed. On this basis the trial judge held that the respondents were entitled to rely on the defence, if proven.
 We agree. In their amended statement of defence and counterclaim the respondents asserted that they were unaware that they had personally guaranteed Carter’s Printing’s debt to the appellant and pleaded various circumstances surrounding that assertion. They alleged that the lawyer did not explain the document and did not provide them with an opportunity to read it. The respondents pleaded that they, in fact, signed the guarantee without reading it and it was only later that they learned that they had signed a document in which they personally guaranteed the company’s indebtedness under the promissory note.
 The defence was sufficiently set out to enable the appellant to respond and the record establishes that battle was joined on that issue.
In Holmes v. Hatch Ltd. (Ont CA, 2017) the Court of Appeal reiterated and applied the pleadings principle that all issues to be advanced by a party must be set out in the pleadings so as to give adequate notice of the issue to the other parties:
 The law assumes that the parties’ pleadings properly delineate all relevant claims in dispute and define the issues. In Rodaro v. Royal Bank (2002), 2002 CanLII 41834 (ON CA), 59 O.R. (3d) 74 (C.A.), at para. 60, this court described the operative principle in this fashion:. Midland Resources Holding Limited v. Shtaif
It is fundamental to the litigation process that lawsuits be decided within the boundaries of the pleadings. As Labrosse J.A. said in 460635 Ontario Ltd. v. 1002953 Ontario Inc., 1999 CanLII 789 (ON CA),  O.J. No. 4071 (Ont. C.A.), at para. 9:
The parties to a legal suit are entitled to have a resolution of their differences on the basis of the issues joined in the pleadings. A finding of liability and resulting damages against the defendant on a basis that was not pleaded in the statement of claim cannot stand. It deprives the defendant of the opportunity to address that issue in the evidence at trial.See also A-C-H International Inc. v. Royal Bank (2005), 2005 CanLII 17769 (ON CA), 197 O.A.C. 227; Labatt Brewing Co. v. NHL Enterprises Canada L.P., 2011 ONCA 511 (CanLII), 106 O.R. (3d) 677.
In Midland Resources Holding Limited v. Shtaif (Ont CA, 2017) the Court of Appeal considered the conditions under which unpled causes of action may nonetheless be argued and considered by the court:
 Rule 25.07(4) of the Rules of Civil Procedure requires a defendant to plead any matter on which he intends to rely to defeat the claim of the opposite party and which, if not specifically pleaded, "might take the opposite party by surprise or raise an issue that has not been raised in the opposite party's pleading." This requires a party to plead an affirmative defence, such as a plaintiff's lack of standing to sue: Concord Kitchens GP Inc. v. Eastern Construction Company Limited, 2010 ONSC 2168 (CanLII), at paras. 102-105; Huber v. Way, 2014 ONSC 4426 (CanLII), at paras. 66-68.
 The reason for this pleading rule is quite simple. The just determination of a civil proceeding on its merits requires a fair adjudicative process. Trial by ambush is not fair. Accordingly, trial unfairness may result where a defendant is permitted to rely on an unpleaded defence which, if pleaded, might have prompted counsel to employ different tactics at trial: Strong v. Paquet Estate (2000), 2000 CanLII 16831 (ON CA), 50 O.R. (3d) 70 (C.A.), leave to appeal refused,  S.C.C.A. No. 532, at para. 37. As this court stated in Hav-A-Kar Leasing, 2012 ONCA 826 (CanLII), at paras. 69-70:
The failure to raise substantive responses to a plaintiff’s claims until trial or, worse, until the close of trial, is contrary to the spirit and requirements of the Rules of Civil Procedure and the goal of fair contest that underlies those Rules. Such a failure also undermines the important principle that the parties to a civil lawsuit are entitled to have their differences resolved on the basis of the issues joined in the pleadings…. [W]here a defence to a civil action is not pleaded and no pleadings amendment is obtained, judges should generally resist the inclination to allow a defendant to raise and rely on the unpleaded defence if trial fairness and the avoidance of prejudice to the plaintiff are to be achieved. The rule is not absolute. This court has excused defendants from their failure to raise an affirmative defence in the pleadings where the issue was otherwise clearly raised and put in issue before trial: Reliable Life Insurance Company v. M.H. Ingle & Associates Insurance Brokers Ltd. (2002), 2002 CanLII 41603 (ON CA), 59 O.R. (3d) 1 (C.A.), at para. 36. However, raising a potentially dispositive issue during closing submissions, after the close of evidence, may well prove too late.