The NSW Government tabled figures on the success rate of drug detection dogs in Parliament last year that NSW Police now say were "incorrect" and produced using "untested methodology".

When the Legislative Council resumes for 2020 today, Police Minister David Elliott is expected to table amended figures which show the performance of sniffer dogs in a better light.

Key points: NSW Police has admitted figures provided to Parliament last year on behalf of Police Minister David Elliott regarding drug sniffer dog success rates were "incorrect".

NSW Police has admitted figures provided to Parliament last year on behalf of Police Minister David Elliott regarding drug sniffer dog success rates were "incorrect". The Government is expected to table new figures today, which show drug dog performance in a better light.

The Government is expected to table new figures today, which show drug dog performance in a better light. NSW Police would not explain the differences in methodology used to calculate the two sets of figures, which are substantially different.

The new figures show the dogs got it right 31 per cent of the time after indicating a person was carrying drugs in 2018-19.

The original statistics, contained in a document signed by Mr Elliott and tabled in the Upper House on his behalf by Education Minister Sarah Mitchell in October, showed drugs were found in just 24 per cent of searches in that year.

The Government will table updated figures for the years from 2011-12 to 2018-19, each of which reveals a better success rate for the dogs than originally stated.

The new figures show that drugs were found in 33 per cent of all cases over the eight-year period, compared with 24 per cent in the October figures.

Deputy Coroner's report relied on 'incorrect' figures

The use of drug detection dogs was criticised for leading to so-called "panic ingestion" of drugs by the NSW Deputy Coroner Harriet Grahame in her report last year into the the deaths of six young people at music festivals.

"Having reviewed the evidence, I remain extremely concerned about the practice of drug dog operations at music festivals," Magistrate Grahame said.

Her November 8 report contained a similar figure to the one tabled in Parliament.

"The fact is that in 2018–19 police figures supplied show that in personal searches after drug dog indication, drugs were found in 23.8 per cent of cases" the report said.

Experts have also questioned the success rate of the dogs, including RMIT University lecturer in criminology and justice studies Peta Malins, whose research on drug dogs formed part of Magistrate Grahame's findings.

"[Sniffer dogs] are not at all successful in finding drugs," Dr Malins said last year.

"Many people [at music festivals] get past the dogs with drugs, including some who have described just walking right past a dog with drugs in their pocket."

Unexplained discrepancy

But police have long argued that the dogs' success in detecting drugs justified their use.

The conflicting figures came to light after RMIT ABC Fact Check found claims made NSW Police Commissioner Mick Fuller relating to drug detection dogs to be "overstated".

Mr Fuller claimed on November 19 that the dogs were successful in almost 40 per cent of cases.

In reaching its verdict, Fact Check relied on Mr Elliott's document tabled in Parliament on October 24, which at the time contained the most up-to-date publicly available data.

The original figures were tabled in the Legislative Council on behalf of Police Minister David Elliott. ( ABC News )

The new figures were provided to Fact Check in January under freedom-of-information laws, and more closely align with the commissioner's claim.

But the discrepancies between the two sets of figures are unexplained, with NSW Police saying only that the October figures were developed using "untested methodology" and had not been peer-reviewed.

In a statement, a NSW Police spokesman said:

"The figures relied upon by [Fact Check] in the article dated 11 December 2019 were calculated using untested methodology. "The methodology used was developed differently from that applied on all other occasions to the production of official NSW Police Force statistics, and is unlikely to be progressed for endorsement."

In a letter to the Clerk of the Legislative Council, Mr Elliott said he had been advised in relation to the new data that "the figures provided are accurate and have been obtained using the current methodology".

On the old data, Mr Elliott said the figures had been "developed differently from that applied on all other occasions to the production of official NSW Police Force (NSWPF) statistics".

"NSWPF also advised that the methodology had not been peer reviewed."

Verdict suspended

Both the police and Mr Elliott have declined to answer further questions as to how the methodologies used to develop the two sets of figures differ.

RMIT ABC Fact Check has suspended its verdict on Mr Fuller's claim due to the unsatisfactory explanation.

The unit's director, Russell Skelton, said Fact Check no longer had confidence in the police figures.

"We have asked the police for an explanation as to the difference between the two sets of figures and have not received a satisfactory or transparent response," he said.

"In light of this, we have decided to suspend the verdict from the fact check.

"When a minister tables figures in Parliament, journalists and the public should have confidence they are accurate. A lack of transparency on how incorrect figures came to be tabled only creates further doubt in those figures and erodes public trust in our institutions."

