Chain of custody: what happens when drug exhibits go missing.

The story that prompts the question.

In late September 2026, reports out of Fiji described about 52 kilograms of cocaine missing from a court evidence room in Suva, with more than half of it found to have been replaced by flour. Fiji police have said publicly that the drugs were stolen, that security systems were not working during the relevant period, and that an investigation is underway. No one has been charged. That is a foreign matter, it is under investigation, anyone who may come to be charged is presumed innocent, and this article does not comment on it.

What the story does is put a spotlight on something most people never think about until it goes wrong. Drug prosecutions turn on a physical thing, the drug itself, that has to travel from the point of seizure, through a police exhibit store, to a laboratory, and finally to a courtroom, sometimes over a year or more. The law that governs that journey in Australia is the law of continuity, or chain of custody. This note explains what it requires, and what happens to a case here when the exhibit at the centre of it is lost, tampered with, or cannot be accounted for.

What is chain of custody, or continuity of evidence?

Chain of custody is the record of who handled an exhibit, when they handled it, and how it was stored, from seizure to court. In a drug case it exists to answer one plain question: is the substance in the courtroom the same substance that was taken from the accused? If the prosecution cannot connect the two, the analysis of a white powder proves only that some powder, somewhere, was a drug. It does not prove that the accused had it.

There is no single section of an Act headed continuity. It is built from the seizure record made at the scene, the exhibit register, tamper-evident bagging and its serial numbers, the movement logs of the exhibit store, and the statements of each person who handled the item. Together they let the prosecution trace an unbroken line. Australian courts have long treated that line as a matter that goes to the weight of the evidence, and in a serious case to its admissibility.

How does the prosecution prove a substance is an illegal drug?

The prosecution must prove that the substance is a prohibited drug, or for a Commonwealth import charge a border-controlled drug. That is done by scientific analysis. In New South Wales, section 43 of the Drug Misuse and Trafficking Act 1985 allows an analyst's certificate to be tendered as evidence of the matters set out in it, including the identity and weight of the substance analysed. The ACT and the Commonwealth have their own analysis and certificate arrangements that do the same work.

The certificate is a powerful document, but it proves the content of the sample the analyst tested. It does not prove that the sample the analyst tested is the drug that was seized from the accused. That connection is the continuity evidence. A missing or interfered-with exhibit attacks the connection, not the chemistry. Our notes on possession of a prohibited drug in NSW and on deemed supply under section 29 set out the elements that the analysis and continuity are there to prove.

What does the prosecution have to prove about quantity?

Quantity is not a side issue. It sets the tier of the offence and the maximum penalty. In New South Wales the thresholds run from a small quantity through to an indictable, commercial and large commercial quantity, and the deemed supply provisions turn on the traffickable threshold. For Commonwealth import offences the tiers run from a marketable to a commercial quantity, as our note on the Periasamy sentence appeal describes.

Proving the quantity depends on weighing the actual exhibit, usually the pure weight after analysis for the higher Commonwealth tiers. If the exhibit is gone, the prosecution may be left unable to prove the quantity it has charged. A charge pitched at a commercial quantity can fall away to a lesser tier, or fail on that element, if there is no reliable proof of weight. That is a direct, practical consequence of a lost exhibit.

What happens if a drug exhibit is lost, missing or tampered with?

Two things are in play: admissibility and weight. The starting position in Australian law is that a gap in continuity goes to weight. The evidence can still be admitted, but the defence is entitled to point to the gap and argue that the tribunal cannot be sure the exhibit is what the prosecution says it is. The larger and less explained the gap, the more force that argument has.

A serious break can move from weight to admissibility. Under the Evidence Act 1995 (NSW), and the Evidence Act 2011 (ACT), a court may refuse to admit evidence in a criminal trial where its probative value is outweighed by the danger of unfair prejudice, and may exclude evidence that has been improperly or unlawfully obtained. Interference with an exhibit can also raise a real question of tampering, which the prosecution then has to answer. Our note on DPP v Kan and section 138 looks at how those exclusion discretions run in practice.

Even where the exhibit is admitted, a broken chain can be enough to raise a reasonable doubt. The criminal standard does the work here. The prosecution has to prove identity and quantity beyond reasonable doubt, and a jury that cannot be sure the powder in evidence is the powder taken from the accused is a jury that must acquit.

Can a drug charge be dropped if the evidence goes missing?

Sometimes, but it is not automatic. The prosecution applies a two-part test before running a case: whether there is a reasonable prospect of conviction, and whether a prosecution is in the public interest. If a lost or tampered exhibit means the identity or quantity of the drug can no longer be proved, the first limb may not be met, and the matter can be discontinued or reduced.

If the matter runs, the defence puts the prosecution to proof on continuity. Where the case stands or falls on the missing exhibit, that can support a no-case submission or an acquittal. But a missing exhibit is not a guaranteed end to a case. Other evidence can fill the gap: recorded admissions, clear photographs and weights taken at the scene, presumptive field tests, or an analysis completed before the exhibit was lost. What is left in the brief decides how much the loss actually costs the prosecution. Our note on the brief of evidence explains where those documents sit.

Could what happened in Fiji happen in an Australian court?

This is a question about systems, not about the Fiji matter. Australian jurisdictions run structured exhibit management: secure and access-controlled exhibit stores, tamper-evident packaging with unique numbers, barcoded continuity records, and the destruction of drug exhibits only under a court order or a statutory authority after sampling and analysis. Those controls exist precisely because a drug exhibit is valuable and the case depends on it.

No system removes the risk entirely. Continuity failures do happen here, and they are litigated: an exhibit misplaced between stations, a bag opened without a recorded reason, a weight that does not match across two records. When they happen, the response is not a scandal but a legal one. The defence tests the gap, and the prosecution has to prove the exhibit is what it says it is, or live with the doubt.

What to do if continuity is in issue in your matter.

Get the full brief and read the continuity material closely: the exhibit register, the movement logs, the bagging and its serial numbers, the weighing records, and the analyst's certificate. Check that each handover is accounted for and that the weights and descriptions match from the scene through to the laboratory. A single unexplained step can be the difference between a case that is proved and one that is not.

If there is a gap, it can be raised in representations to the prosecution before trial, in a challenge to the evidence at trial, or in a no-case submission. Each path needs advice on the strength of the rest of the brief. If you are charged with a drug offence and the exhibit or its handling is in question, get advice early, while the records can still be obtained and tested.

Frequently asked.

What is chain of custody in a drug case?

Chain of custody, also called continuity of evidence, is the unbroken record of who handled an exhibit, when, and how it was stored, from seizure to court. In a drug case it is how the prosecution shows that the substance analysed and tendered is the same substance taken from the accused. It is built from seizure records, exhibit registers, storage logs and the evidence of the people who handled the item.

How does a court prove a substance is an illegal drug in Australia?

Through scientific analysis. In New South Wales an analyst's certificate under section 43 of the Drug Misuse and Trafficking Act 1985 is evidence of the matters stated in it. The certificate proves what was in the sample analysed, and the prosecution must also prove that the sample analysed came from the drug seized from the accused, which is the continuity evidence.

Can a drug charge be dropped if the drugs go missing?

It can, but not automatically. If continuity cannot be proved, the prosecution may not meet its test of a reasonable prospect of conviction and may discontinue. At trial the defence can put the prosecution to proof, and if the case depends on the missing exhibit a no-case submission or an acquittal may follow. It depends on what other evidence exists, such as admissions, photographs, field tests or an analysis done before the exhibit was lost.

Does a break in the chain of custody make the evidence inadmissible?

Not usually on its own. Australian courts generally treat a gap in continuity as going to the weight of the evidence rather than its admissibility. A serious break can be different. Under the Evidence Act a court may refuse to admit evidence where its probative value is outweighed by the danger of unfair prejudice, and a large unexplained gap may leave the tribunal unable to be satisfied of identity or quantity beyond reasonable doubt.

Who proves the weight of the drugs, and why does it matter?

The prosecution proves weight, because the quantity sets the tier of the offence and the maximum penalty. The thresholds run from a small quantity up to a large commercial quantity in New South Wales, and from marketable to commercial for Commonwealth import offences. Proving the quantity depends on weighing the actual exhibit, so if the exhibit is missing the prosecution may be unable to prove the quantity it has charged.

Is an analyst's certificate enough on its own?

The certificate proves the nature and quantity of what was analysed. It does not, by itself, prove that what was analysed is what was taken from the accused. That link is the continuity evidence. Where the exhibit has since gone missing or been interfered with, the defence can test whether the prosecution can still connect the certificate to the drug allegedly in the accused's possession.

To speak to a criminal defence lawyer, call Aaron Kernaghan on 0421 717 019.

This article is written by Aaron Kernaghan, criminal defence lawyer at Brady & Associates Lawyers, as at 30 September 2026. It is commentary and reflects the personal opinion of the author only. It is not legal advice, it is not a substitute for advice on your own matter, and it does not purport to be accurate or complete. Any matter referred to may be before the court and any person charged is presumed innocent. For advice on a specific matter, contact Aaron Kernaghan on 0421 717 019 or contact the firm.

More criminal-law commentary by Aaron Kernaghan.

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