Western Australia, Australia

Can entrapment be used as a defence to a drug charge in Western Australia?

Police involvement in an alleged drug offence does not automatically end a prosecution. The conduct of the operation, the evidence and the applicable law all matter.

Published 27 October 2026

Undercover drug buys can involve police posing as buyers or sellers and gathering evidence through the interaction. A person charged after such an operation may assume that police initiating or facilitating the transaction creates an automatic defence. Australian law takes a different approach.

What does entrapment mean?

The word “entrapment” is often used to describe police inducing an offence, rather than simply providing an opportunity to someone willing to offend. It is not a shortcut to deciding a case: the actual conduct, the elements of the alleged offence and the law governing the investigation need to be examined.

Why it is not a standalone defence in Australia

Australian law does not recognise a standalone substantive defence of entrapment. In Ridgeway v The Queen (1995) 184 CLR 19, the High Court recognised a public-policy discretion to exclude evidence where law enforcement officers unlawfully procured an offence. The Court later explained these principles in Gedeon v Commissioner of the New South Wales Crime Commission [2008] HCA 43, paragraphs 2–3.

That distinction does not mean relief is unavailable. An evidentiary ruling can affect whether a prosecution can prove its case. The result depends on the circumstances and the applicable legislation; police participation alone neither establishes a defence nor settles admissibility.

Anyone facing a drug charge after an undercover operation should seek advice about the evidence and the law that applies to their case. For information about legal services in Perth, visit our Perth team at Podmore Legal — Perth criminal defence specialists in drug offence matters.

Undercover operations in Western Australia

WA has a statutory framework for controlled operations under the Criminal Investigation (Covert Powers) Act 2012. Not every undercover interaction is necessarily an authorised controlled operation.

Section 12 sets conditions for granting an authority. These include limits on inducing criminal activity that a person could not reasonably have been expected to engage in without the inducement.

Section 8 preserves courts’ evidence and stay discretions, subject to an important qualification: where its conditions are met, the fact that evidence resulted from a participant’s authorised controlled criminal conduct must be disregarded when deciding admissibility. Authorisation and its limits therefore matter; the older case law cannot be applied without considering the statute.

When could evidence be challenged?

A lawyer assessing an undercover operation may need to examine the authority, what conduct was permitted, what actually occurred and how the evidence was obtained. Whether an exclusion argument or another remedy is available depends on the facts and law. A concern about police conduct does not automatically invalidate all evidence or require a charge to be dismissed.

What this means if you have been charged

Do not assume that an undercover officer’s involvement resolves the case. Seek advice from a lawyer practising in the relevant jurisdiction, who can examine the charge, the evidence and any available challenge. General descriptions of entrapment, particularly those drawn from US film and television, are not a substitute for that assessment.

Related reading: police drug search powers, possession with intent to supply, excluding unlawfully obtained evidence, our Virginia criminal law overview, and the TroofLaw blog.