Although the extract from the following general protections case is a little dated now, it continues to be one of the most persuasive summaries of the purpose (and therefore the limitations) of a general protections case.
“As I said in Ermel v Duluxgroup (Australia) Pty Ltd (No 2)  FCA 17 at , in relation to a claim brought pursuant to s 340 of the FW Act:
[S]uccess depends upon the Court being satisfied that the applicant has been subjected to adverse action for one or more of the specific reasons identified by the FW Act as an impermissible basis upon which action adverse to the applicant may be taken. A general protections proceeding is not a broad enquiry as to whether the applicant has been subjected to a procedurally or substantively unfair outcome”.
Gray, Cowdroy and Reeves JJ made similar observations in Khiani v Australian Bureau of Statistics  FCAFC 109 at :
A general protections application is not intended to provide an opportunity for the appellant to raise whatever issues she wishes to about the validity of the steps taken before her dismissal. The crucial issue in such an application is the causal relationship between adverse action and one or more of the factors mentioned in the various provisions of Pt 3-1. The issue is whether the person who has taken the adverse action has done so because the person against whom the adverse action has been taken has one or more of the relevant characteristics or has done one or more of the relevant acts.
Moreover, proceedings in relation to civil penalty provisions under the FW Act are penal in nature. Allegations of contravention of the general protections provisions are inherently serious and should, as a matter of fairness, be pleaded with sufficient precision for a respondent to know the case against it. So much was made clear by the Full Court (Logan, Bromberg and Katzmann JJ) in Construction, Forestry, Mining and Energy Union v BHP Coal Pty Ltd  FCAFC 25; (2015) 230 FCR 298 at – (emphasis added):
 Even so, a civil suit for the recovery of a pecuniary penalty is a proceeding of a penal nature: Naismith v McGovern  HCA 59; (1953) 90 CLR 336 at 341. In this class of case, it is especially important that those accused of a contravention know with some precision the case to be made against them. Procedural fairness demands no less.Furthermore, although the civil standard of proof applies, where (as here) the resolution of an issue exposes a respondent to a penalty, satisfaction on the balance of probabilities is not achieved by “inexact proofs, indefinite testimony, or indirect inferences”:Briginshaw v Briginshaw  HCA 34; (1938) 60 CLR 336 at 362. The Evidence Act 1995(Cth) now requires that the court take into account the nature of the cause of action in deciding whether it is satisfied that a party’s case has been proved on the balance of probabilities: Evidence Act 1995 (Cth), s 140(2)(a) (“Evidence Act”).
 Litigation is not a free for all. The overarching purpose of the civil practice and procedure provisions that apply in this Court is to facilitate the just resolution of disputes according to law and as quickly, inexpensively and efficiently as possible (Federal Court of Australia Act 1976 (Cth) (“FCA Act”), s 37M). It would not be just to decide a case on a different basis than the way it was conducted. Nor would it be just to permit an applicant to change the nature of its case after the evidence has closed and its weaknesses pointed out, at least not without a formal application and the grant of leave, on terms if necessary.
 The long and the short of it, then, is that, in a civil proceeding of a penal nature, a statement of claim must allege a contravention known to law and with a sufficient statement of material facts to alert a respondent to the case to be met. Nevertheless, where an applicant’s pleading is ambiguous but a respondent has nonetheless meaningfully engaged with it in its defence, that engagement and the manner in which an applicant’s case is consequentially opened and the trial conducted and defended can and ought to be considered in deciding whether a respondent has suffered any procedural unfairness. That is so even if there has been no formal application to amend the pleading. The obligations imposed on the Court and the parties by Pt VB of the FCA Act do not lead to any different conclusion.”
Celand v Skycity Adelaide Pty Ltd  FCAFC 222 delivered21 December 2017 per Bromberg J