[68] Once the distinction between jurisdiction as a "threshold requirement" and choice of law is appreciated, it will be seen that there is no obligation upon either party to plead foreign law in order to render a claim or cross-claim justiciable. If, however, either party seeks to rely on foreign law, rules of court and general principles of pleading may oblige the party to plead the relevant foreign law. As is said in Bullen & Leake & Jacob's Precedents of Pleadings:
"Where a party relies on foreign law to support his claim or as a ground of defence thereto, he must specially plead the foreign law relied on in his statement of claim or defence, as the case may be, and he should give full particulars of the precise statute, code, rule, regulation, ordinance or case law relied on, with the material sections, clauses or provisions thereof. A mere allegation that an instrument depending on foreign law is null and void is too vague."
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[69] Two particular questions arise respecting the pleading of foreign law in tort actions.
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[70] The first question is whether it is necessary for the plaintiff to plead the foreign law in order to establish a cause of action. The answer preferred by Dicey is in the negative. In Walker v W A Pickles Pty Ltd, Hutley JA explained101:
"An action of tort may be brought in New South Wales courts irrespective of where the facts founding the action may have occurred, even if they occurred in a place where there may be no law at all: see Mostyn v Fabrigas. A pleading of a cause of action in tort which did not allege that the facts occurred in any particular law district would be formally valid. On the basis that the utmost economy is enjoined by the rules, it would seem to me that pleading of a foreign element in the initiating process in a claim in tort can never be necessary. ...
This approach is reinforced by the principle that foreign law, which is, except between the States and the Territories of the Commonwealth, a fact, is presumed to be the same as local law; and a fact presumed to be true does not have to be pleaded: See Supreme Court Rules, Pt15, r10(a).
On the other hand, if the defendant seeks to rely upon a foreign lex causae, then, in the ordinary way, it is for the defendant to allege and prove that law as an exculpatory fact.