“ Issue estoppel may arise where a particular issue forming a necessary ingredient in a cause of action has been litigated and decided and in subsequent proceedings between the same parties involving a different cause of action to which the same issue is relevant one of the parties seeks to re-open that issue. This form of estoppel seems first to have appeared in Duchess of Kingston's Case (1776) 20 St.Tr. 355. A later instance is Reg. v. Inhabitants of the Township of Hartington Middle Quarter (1855) 4 E. & B. 780. The name "issue estoppel" was first attributed to it by Higgins J. in the High Court of Australia in Hoysted v. Federal Commissioner of Taxation(1921) 29 CLR 537 , 561. It was adopted by Diplock L.J. in Thoday v. Thoday [1964] P. 181. Having described cause of action estoppel as one form of estoppel per rem judicatam, he said, at p. 198: “The second species, which I will call 'issue estoppel,' is an extension of the same rule of public policy. There are many causes of action which can only be established by proving that two or more different conditions are fulfilled. Such causes of action involve as many separate issues between the parties as there are conditions to be fulfilled by the plaintiff in order to establish his cause of action; and there may be cases where the fulfilment of an identical condition is a requirement common to two or more different causes of action. If in litigation upon one such cause of action any of such separate issues as to whether a particular condition has been fulfilled is determined by a court of competent jurisdiction, either upon evidence or upon admission by a party to the litigation, neither party can, in subsequent litigation between one another upon any cause of action which depends upon the fulfilment of the identical condition, assert that the condition was fulfilled if the court has in the first litigation determined that it was not, or deny that it was fulfilled if the court in the first litigation determined that it was ."”
“ In Mills v. Cooper [1967] 2 Q.B. 459 the question arose whether the respondent, having been found by magistrates not to have been a gypsy on a certain date upon which he had been charged with unlawfully encamping on a highway, had the protection of issue estoppel in relation to a similar charge relating to a later date. It was held that the status of gypsy was not an unalterable one, so that the respondent might well be a gypsy at one time though not at another. Diplock L.J. made the following general observation about issue estoppel, at pp. 468-469: "That doctrine, so far as it affects civil proceedings, may be stated thus: a party to civil proceedings is not entitled to make, as against the other party, an assertion, whether of fact or of the legal consequences of facts, the correctness of which is an essential element in his cause of action or defence, if the same assertion was an essential element in his previous cause of action or defence in previous civil proceedings between the same parties or their predecessors in title and was found by a court of competent jurisdiction in such previous civil proceedings to be incorrect, unless further material which is relevant to the correctness or incorrectness of the assertion and could not by reasonable diligence have been adduced by that party in the previous proceedings has since become available to him." In Hunter v. Chief Constable of the West Midlands Police[1982] AC 529 , 541, Lord Diplock said, with the concurrence of the other members of the House, that this passage had been adopted and approved by your Lordships' House in Reg. v. Humphrys[1977] A.C 1 .”