Maintaining the integrity of the legal system is a core priority of the Western Australian justice system. When an individual takes deliberate actions to disrupt, interfere with, or manipulate a police investigation or court proceeding, they can be charged with a serious indictable offense.
In Western Australia, this conduct is prosecuted under the charge of Attempting to Pervert the Course of Justice (often referred to colloquially as obstructing justice). Because this offense strikes directly at the administration of law, WA courts treat it with a high degree of severity, frequently imposing immediate custodial sentences for proven offenders.
The Legal Definition Under WA Law
The offense is governed strictly by statutory law rather than common law definitions. Under Section 143 of the Criminal Code Act Compilation Act 1913 (WA), the law states:
Any person who attempts to obstruct, prevent, pervert, or defeat the course of justice is guilty of a crime.
The phrase “course of justice” is interpreted broadly by the courts. It is not limited strictly to the duration of a trial inside a courtroom. The course of justice begins the moment a crime is committed, an investigation is initiated by the Western Australia Police, or a judicial process is set into motion.
Common Examples of Perverting the Course of Justice
The charge can apply to a wide variety of behaviors across different stages of the legal process. Common real-world examples include:
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Interfering with Witnesses: Threatening, bribing, or placing undue pressure on a witness to alter their testimony, give a false statement, or refuse to attend court.
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Fabricating or Destroying Evidence: Disposing of electronic devices, wiping surveillance footage, hiding physical evidence, or manufacturing false documents to mislead investigators.
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Providing a False Alibi: Conspiring with friends or family members to provide a false timeline to police to steer suspicion away from a suspect.
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Falsifying Statutory Declarations: Submitting a false declaration to avoid traffic penalties, such as falsely naming another person as the driver of a vehicle during a speeding or red-light camera offense.
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Bribing Officials: Offering money or favors to police officers, court staff, or jurors to influence the outcome of an investigation or trial.
Maximum Penalties and Sentencing Trends
Because the crime directly undermines the public’s confidence in the legal system, it carries heavy statutory penalties.
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Maximum Penalty: 7 years imprisonment.
Indictable Nature and Jurisdiction
Attempting to pervert the course of justice is a strictly indictable offense in Western Australia. This means it cannot be finalized in the Magistrates Court.
While the initial arrest, bail application, and administrative mentions occur in the Magistrates Court, the matter must ultimately be committed to the District Court of Western Australia for final determination, whether through a trial or a sentencing hearing following a plea of guilty.
Sentencing Considerations
When determining the appropriate penalty, a District Court judge will evaluate the specific context of the offending. The court looks at several critical aggravating and mitigating factors:
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The Level of Premeditation: Sophisticated, planned, and ongoing efforts to mislead police are penalized more harshly than spontaneous, panic-driven decisions.
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The Nature of the Underlying Offense: Attempting to obstruct an investigation into a minor traffic matter is viewed differently than attempting to subvert a homicide or major drug trafficking trial.
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The Target of the Conduct: If the offender targeted a vulnerable witness or a juror, the court will place significant weight on general deterrence, making an immediate prison sentence highly likely.
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Success or Failure: It is a fundamental principle of this offense that the success of the attempt does not dictate the penalty. The offense is completed by the attempt itself. The court measures seriousness by the potential consequences to justice if the plan had succeeded.
What the Prosecution Must Prove
To secure a conviction under Section 143 of the Criminal Code, the state prosecution (the State Solicitor’s Office or the Director of Public Prosecutions) must establish two core elements beyond a reasonable doubt:
1. The Physical Element (Actus Reus)
The prosecution must prove that the accused person performed an act that had the tendency to obstruct, prevent, pervert, or defeat the course of justice. This requires showing a clear, overt action—such as sending a threatening text message to a witness or physically discarding a piece of evidence.
2. The Mental Element (Mens Rea)
The prosecution must prove that the accused intended to produce that exact outcome. The individual must have known, or fully intended, that their actions would result in the course of justice being subverted.
Important Legal Distinction: The police do not need to prove that the course of justice was actually affected or derailed. For example, if a person attempts to bribe a police officer, but the officer refuses the bribe and reports the incident immediately, the offense is still completely satisfied. The intention to cause the obstruction is what constitutes the crime.
Legal Defences under Western Australian Law
Facing a charge under Section 143 requires a meticulous analysis of the evidence collected by police. A highly strategic criminal defense involves identifying weaknesses in the prosecution’s brief. Several established defenses may apply depending on the facts of the case:
Lack of Intention
If the defense can demonstrate that the accused did not intend to interfere with a legal proceeding, the charge cannot stand. For example, if an individual accidentally deletes security footage as part of a routine data-purging cycle without knowing it was sought for an active investigation, they lack the necessary criminal intent (mens rea).
Factual Dispute and Identification
In many cases, particularly those involving digital communication or witness interference, the core defense rests on identity. If the prosecution relies on anonymous phone calls, encrypted messages, or unverified accounts, the defense can challenge whether the evidence conclusively links the accused to the prohibited act.
Duress
The defense of duress applies if the accused person was forced to perform the obstructing act because of an immediate threat of death or grievous bodily harm to themselves or their family. If a person provides a false alibi solely because they were being held under physical coercion by a violent offender, the law may excuse the conduct.
Total Impossibility vs. Mistaken Belief
It is not a defense to argue that the attempt could not have succeeded because of external factors. However, a distinction can sometimes be made if the actions taken could not, under any objective legal standard, have had a tendency to pervert a real course of justice (for instance, if no investigation existed, was contemplated, or could logically flow from the circumstances).
Strategy for Managing an Active Charge
If you or someone you know is being investigated or has been formally charged with attempting to pervert the course of justice in WA, the early steps taken are critical to the trajectory of the matter.
1. Exercise the Right to Silence
Statements made during an initial police interview can easily inadvertently satisfy the prosecution’s requirement to prove intent. Because the legal definition hinges tightly on what the accused intended to achieve, engaging in a formal interview without legal representation poses a significant risk.
2. Secure and Preserve Independent Evidence
If the defense relies on a lack of knowledge or an alternate timeline, preserving phone records, email logs, and workplace data early ensures that critical corroborating evidence is not overwritten or lost.
3. Evaluate the Strength of the Prosecution’s Case
A criminal defense barrister will review the brief of evidence to see if the state can definitively prove that an overt act occurred and that it was accompanied by a purposeful intent to mislead. If the evidence is circumstantial or relies heavily on uncorroborated witness statements, contesting the matter at a District Court trial may be the most viable path.