R v. Kringuk, 2011 NUCJ 13 has some very helpful language on oppression and voluntariness:
 The common law has long required the Crown to prove beyond a reasonable doubt that any statements made by a suspect to investigating authorities are made freely and voluntarily. No statement made by an accused is admissible for any purpose unless the Crown meets this formidable burden of proof. The Supreme Court of Canada, in the case of R v Oickle,  2 SCR 3, 2000 SCC 38, confirmed that the primary purpose of this requirement is to ensure that any statement gathered by the forces of the state, directly from an accused, remains reliable and trustworthy.
 Our collective human experience tells us that where there is a choice, people do not ordinarily volunteer information that is harmful to themselves. When they freely choose to do so, it is usually because the information is true, or they believe it to be true. The common law adopts this behavioural model.
 The common law focus on voluntariness ensures that a statement given to the authorities is made in circumstances where reliability is enhanced. Reliability depends upon the speaker being free of corrupting influences or pressures that might affect either the decision to speak or the quality of information provided by the speaker.
 To achieve reliability, the common law first gives some protection to the citizen's right to remain silent. It is this right which gives life to the choice upon which reliability depends. The common law then demands that an environment free of corrupting or adverse influences be available for the citizen to make the decision to speak. This environment is regulated through the application of the voluntariness requirement. It is the broad and flexible application of this requirement that ensures optimum conditions are present if a statement against interest is made.
 The citizen's freedom of choice is protected by ensuring that the decision to speak to the authorities is not influenced by the forces of the state through threats or promises that instill a hope of advantage, or a fear of prejudice. A prisoner will be tempted to provide information if there is some perceived advantage in doing so. Information desired by the authorities, whether accurate or not, may be given to secure the offered benefit or to avoid a threatened consequence. Truth may be lost in the resulting bargain. Reliability under these circumstances cannot be assured.
 This freedom of choice is protected by ensuring that a citizen's treatment, at the hands of the authorities, is not so punitive that a prisoner is induced to speak and give false information to avoid further ill treatment. The common law's long experience confirms that the reliability of information provided by prisoners is undermined by considerations related to securing more favourable treatment. Under oppressive conditions, the prisoner's freedom of choice becomes illusory. In the hope of improving his or her lot, the prisoner is induced to give his or her captors what they are seeking. The common law has learned over many years and many cases, that a statement made under these circumstances is inherently unreliable and more likely to be false than true.
 This freedom of choice is protected by insisting that the authorities avoid the use of strategies designed to psychologically overwhelm the citizen. A false portrayal of invincibility or infallibility may lead a citizen to conclude that it is utterly futile to remain silent, or to deny the undeniable. A reference to false or nonexistent evidence, to the infallibility of police forensic sciences, or the use of tricks, may all induce a false confession.
 A citizen who is deliberately exposed to this treatment has been primed to accept the inevitable. When confronted by what purports to be overwhelming evidence of guilt and the inevitability of conviction, self-doubt sets in. Despair and resignation soon follow. The citizen's decision to speak is likely to be influenced by this. The prisoner may create a false reality to match what the authorities expect. History confirms that truth is readily sacrificed upon an altar of greater expediency. In the experience of the common law, the false confession has proven to be one of the greatest single contributors to wrongful convictions.
 Protection of this freedom of choice is achieved by ensuring that a citizen has sufficient cognitive capacity to understand that a choice is in fact involved. The requirement that the citizen possess an 'operating mind' ensures that subjective psychological, psychiatric or physiological conditions do not deprive the citizen of any ability to make a choice to speak. Where there is no capacity to make a choice, the behavioural model underlying the common law test for reliability cannot be applied. The result can only be uncertainty and unreliability.
 The many facets of the common law voluntariness requirement, the traditional Ibrahim rule (Ibrahim v The King,  AC 599,  UKPC 1), the doctrine of oppression, and the requirement of an operating mind, all promote the reliability of statements made to authorities through preservation of this choice to speak or not. A statement against interest must be the product of a conscious decision to speak. It must result from a choice that is free from any corrupting influences or pressures. It is only in this way, and under these circumstances, that the common law can be assured that statements against interest reflect accuracy and truth, not falsehood or misinformation.