24 / 11 / 2023

Excluding improperly obtained evidence 

The integrity of a judicial system relies heavily on the assurance that evidence presented during a trial adheres to legal and ethical standards. In many jurisdictions, including New South Wales, a mechanism exists in the Evidence Act 1995 (NSW) that allows the Court to exclude improperly or illegally obtained evidence. It is an important discretionary power and safeguard.

The discretion to exclude improperly or illegally obtained evidence is crucial to ensuring fairness in legal proceedings.  Under s 138 of the Evidence Act 1995 (NSW), a Judge or Magistrate has the authority to determine the admissibility of evidence that may have been obtained in violation of a person’s rights or otherwise through unlawful means.

Improperly or illegally obtained evidence encompasses a broad spectrum of situations, including:

  • Evidence Obtained Without a Warrant: When authorities collect evidence without the proper legal authorisation or a valid search warrant.
  • Unlawful Interviews: Evidence that is obtained during a police interview that does not adhere to established legal procedures, such as failing to caution the suspect or inform them of their rights.
  • Violations of the Right to Silence: Answers provided by an individual to police in the face of persistent questioning when they have attempted to exercise their right to silence.

Discretionary Power

The discretion to exclude improperly or illegally obtained evidence operates as a two-stage process in New South Wales:

  1. Determining whether the evidence was illegally or improperly obtained: the Court will first examine the circumstances surrounding the acquisition of the evidence to ascertain whether it was obtained improperly or illegally.  Usually, this will involve extensive cross-examination of the persons (often police officers) who obtained the evidence.
  2. The balancing act: If it is established that the evidence was obtained improperly or illegally, the Court then performs a balancing act to decide whether the evidence should be admitted in the trial.  In this balancing act, the Court must consider the following:
    • (a)  the probative value of the evidence;
    • (b)  the importance of the evidence in the proceeding;
    • (c)  the nature of the relevant offence, cause of action or defence and the nature of the subject-matter of the proceeding; and
    • (d)  the gravity of the impropriety or contravention; and
    • (e)  whether the impropriety or contravention was deliberate or reckless; and
    • (f)  whether the impropriety or contravention was contrary to or inconsistent with a right of a person recognised by the International Covenant on Civil and Political Rights; and
    • (g)  whether any other proceeding (whether or not in a court) has been or is likely to be taken in relation to the impropriety or contravention; and
    • (h)  the difficulty (if any) of obtaining the evidence without impropriety or contravention of an Australian law.

In many cases, a strong argument can and should be made to exclude evidence that has been improperly or illegally obtained.  Courts must vigorously protect an accused person’s rights and maintain the integrity of the justice system.

In some cases, the Court may decide not to exclude improperly or illegally obtained evidence if there are compelling reasons not to do so.  Such reasons may include the necessity of protecting public safety or preserving the rights of others.

The discretionary power to exclude improperly or illegally obtained evidence is fundamental to our legal system. The strict application of this discretionary power is designed to protect the rights of the accused, maintain the integrity of the justice system and safeguard individual liberties. It is an essential tool for maintaining fairness and justice in legal proceedings.

Sian O’Shaughnessy, Senior Lawyer