Related Rule
New Zealand
Practice Relating to Rule 100. Fair Trial Guarantees
Section A. General
New Zealand’s Military Manual (1992) states:
No sentence may be passed and no penalty may be executed on a person found guilty of a penal offence related to the conflict except pursuant to a conviction pronounced by an impartial and regularly constituted court, respecting the generally recognized principles of regular judicial procedure. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1137(4).
The manual further provides that it is a grave breach “to deprive [a prisoner of war] of his rights to a fair and regular trial” and to “wilfully deprive a protected civilian of the rights of fair and regular trial”. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, §§ 1702(2) and 1702(3)(d).
The manual also states that depriving “any person protected by the [1949 Geneva] Conventions or the [1977 Additional] Protocol [I] of a fair and regular trial” is a grave breach of the 1977 Additional Protocol I. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1703(4)(e).
With regard to non-international armed conflicts, the manual restates the provisions of common Article 3 of the 1949 Geneva Conventions. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1807(1)(d).
New Zealand’s Geneva Conventions Act (1958), as amended in 1987, provides:
Any person who in New Zealand or elsewhere commits, or aids or abets or procures the commission by another person of, a grave breach of any of the [1949 Geneva] Conventions or of [the 1977 Additional Protocol I] is guilty of an indictable offence. 
New Zealand, Geneva Conventions Act, 1958, as amended in 1987, Section 3(1).
Under New Zealand’s International Crimes and ICC Act (2000), war crimes include the crimes defined in Article 8(2)(a)(vi) and (c)(iv) of the 1998 ICC Statute. 
New Zealand, International Crimes and ICC Act, 2000, Section 11(2).
In its judgment in the X v Refugee Status Appeals Authority in 2006, New Zealand’s High Court in Auckland stated:
[42] I am satisfied that the right to a fair ultimate trial is absolute and that New Zealand law will not permit conduct in this country which will imperil such right, whether the trial is to take place here or elsewhere. There are a number of pointers, all to the same conclusion.
International law
[43] On 11 December 1946 the General Assembly of the United Nations, having affirmed the principles of international law recognised by the “Charter of the Nurnberg Tribunal”, directed the formulation of such principles. In 1950 the International Law Commission of the United Nations did so. The principles formulated included:
Principle V
Any person charged with a crime under international law has the right to a fair trial on the facts and the law.
[44] In R v Bow Street Magistrate, ex parte Pinochet (No 3) [2000] 1 AC 147, 197 Lord Browne-Wilkinson cited the Nuremberg principles of international law. He observed that while the concept of personal liability under international law for international crimes is of comparatively recent growth, at least from the date of the General Assembly’s affirmation, the concept of personal liability for a crime under international law must have been part of international law.
[45] The same must apply to the principles formulated as to the rights of an accused. The Lords’ approach in Pinochet is consistent, for present purposes, with the recent recognition of the Geneva Conventions as part of the domestic law of the United States of America in Hamdan v Rumsfeld 126 S Ct 2749 (2006) (case 05-184). The discussion of Pinochet in Jones v Ministry of the Interior Al-Mamlaka Al-Arabiya as Saudiya (the Kingdom of Saudi Arabia) [2006] 2 WLR 1424 (HL) leaves the present point unaffected.
[46] Article 11(1) of the Universal Declaration of Human Rights requires that:
Everyone charged with a penal offence has the right to … a public trial at which he has had all the guarantees necessary for his defence
and art 14 of the International Covenant on Civil and Political Rights requires that:
… everyone shall be entitled to a fair and public hearing …
and is entitled:
… not to be compelled to testify against himself …
As expressions of the right to a fair trial these must be regarded not merely as undertakings by the states which, like New Zealand, have acceded to the treaties but as rules of international law.
[47] It is true that international law does not, as such, become part of New Zealand domestic law. But as Scarman LJ observed in Thai-Europe Tapioca Service Ltd v Government of Pakistan [1975] 1 WLR 1485, 1495 (CA):
… a rule of international law, once incorporated into our law by decisions of a competent Court, is not an inference of fact but a rule of law. It therefore becomes part of our municipal law …
Given the status of the Nuremberg principles and the decisions in Pinochet and Hamdan, I accept Mr Illingworth’s submission that the right to a fair trial must be accepted via international law as a rule of New Zealand law.
[48] The importance of that conclusion is that it relieves X from having to rely on either rules of the common law or the New Zealand Bill of Rights Act to establish his right in New Zealand to ensure that nothing occurring in this state will impede a fair trial of any genocide charges, if pursued. But I am satisfied that both the common law and the Bill of Rights require the same conclusion. 
New Zealand, High Court Auckland, X v Refugee Status Appeals Authority, Judgment, 14 July 2006, §§ 42–48.