Interpretation — Of municipal statutes — Joint venture agreement between government and private company for erection of synthetic gasoline plant and sale of product — Agreement containing favourable rights of purchase for company — Subsequent deregulation of industry and legislation prohibiting contracts or arrangements having the “likely effect of substantially lessening competition in a market” — Rules of interpretation — Meaning of “likely” Meaning of “substantially lessening” — Identification of “relevant market” Whether purchase rights likely to have effect of substantially lessening competition in a market — Whether agreement rendered unenforceable

Municipal law — Interpretation of contractual terms — Rules of interpretation — Presumption that parties intended reasonable, commercially rational and economically logical result — Interpretatin of statutes — Rules of interpretation — Intrinsic and extrinsic interpretation — Requirement of fair, large and liberal construction to ensure attainment of Act in accordance with true meaning, intent and spirit — New Zealand Acts Interpretation Act 1924 Section 5(j)

State responsibility — For breach of contract — Joint venture agreement between government and private company for erection of synthetic gasoline plant and sale of product — Agreement containing favourable rights of purchase for company — Government deregulating industry and enacting legislation prohibiting arrangements likely to lessen competition — Government pleading subsequent unenforceability of agreement and refusing to pay price adjustments under purchase rights — Whether agreement rendered unenforceable by legislation — Whether government entitled to take advantage of its own actions to render agreement unenforceable