Sometimes, engineers work as consultants to give expert supporting evidence in appropriate circumstances. EIT Course Coordinator and On-Campus Lecturer Dr. Milind Siddhpura shared his experience as an expert witness.

Engineers are professionals who innovate and invent to improve the quality of life for individuals and communities. Their ability to use scientific principles to solve complex problems makes them valuable as expert witnesses in court cases.

In this article, we will discuss the role of engineers as expert witnesses based on the experience of EIT Course Coordinator and On-Campus Lecturer Dr. Milind Siddhpura, who provided his opinion on using a gel-blaster toy gun in a case.

With over 20 years of substantial and internationally significant experience in mechanical engineering, it made sense that Dr. Siddhpura was requested to provide his opinion on using a gel-blaster toy gun.

The case, which according to guns and hunting magazine, Sporting Shooters, has since been deemed “patently absurd nonsense” by the ruling judge, found New South Wales Australia resident Adam Smith guilty of firearms charges under the technicalities of the law.

By law, expert witnesses are neutral and impartial servants of the court.

What Is an Expert Engineer Witness

Expert engineers who serve as witnesses can be expected to express opinions about matters they have exceptional knowledge of, unlike fact witnesses whose testimony is limited to personal observations or experience. Professional Engineers Ontario, a regulatory body for professional engineering in Canada, states that expert witnesses must interpret technical information for those needing help understanding it and applying it to the matter.

In their role as expert witnesses, the engineer must ensure that the evidence presented is understandable, reasonable, balanced, and substantiated by the evidence. Experts must remain neutral and impartial servants of the court or tribunal they appear before rather than representatives or advocates of the party that hired them.

“The witness’ role goes beyond merely answering counsel’s questions to ensuring that participants in the proceedings – either judge and jury or chair – and panel, adequately understand the technical information or opinion being offered,” they said in a document titled The Professional Engineer as an Expert Witness. Experts must understand that their role is to be neutral and impartial servants of the court or tribunal they appear before, not representatives or advocates of the party hiring them.

“The court can determine whether a person offered as an opinion witness will be needed or likely to provide opinions relevant to the proceedings. Since 2011, courts have developed high expectations about the impartiality and neutrality of expert witnesses. This expectation is based on the inability of courts or tribunals to challenge an expert’s opinion directly [because of their lack of expertise],” stated the document.

How EIT Became Involved

A group of prominent lawyers from New South Wales approached EIT with a request to find engineering experts who could investigate the pneumatic systems used in gel blaster guns for a court case. Dr. Siddhpura, a mechanical engineering academic, was interested in solving real-life problems as a part of his consultancy work and took on this challenge. After several initial meetings with the team of lawyers, they asked Dr. Siddhpura to write an expert report.

Dr. Siddhpura recalled, “The lawyers requested an ‘Independent Expert Report’ to investigate the mechanism and operation of various gel blaster guns to determine if these guns are dangerous and should be classified as firearms.”

Before starting his investigation, Dr. Siddhpura declared to the lawyers that his research would be unbiased and that its conclusions may or may not be in their favor. His study would be based on scientific and engineering facts and analysis.

EIT Course Coordinator and On-Campus Lecturer Dr. Milind Siddhpura.

Dr. Siddhpura and his colleague, Dr. Arti Siddhpura, studied all the critical parameters of gel blaster guns, including pressure, velocity, mass, kinetic energy, impact force, and impulse, with technical inputs and support.

They compared these parameters with a range of other types of guns and computed and analyzed the ‘Hornady Index of Terminal Standards Number for various guns to compare the killing power of these guns.

In his 15-page report, Dr. Siddhpura presented the following key findings to the court:
● The gel blaster guns’ level of injury due to the key parameters (pressure, velocity, mass, kinetic energy, impact force, and impulse) was significantly less than all other guns, including traditional air guns.
● The killing power of the gel blaster guns was negligible and could only be compared to NERF toy guns.
● The gel blasters should be identified as a toy rather than classified as air guns.
● The gel blasters should not be regulated under the Firearms Act 1996.
● For gel blasters, a new category called toy guns or imitation guns should be introduced.

The Outcome of The Court Case

Handing over documents in court
A stock image of people handing over documents in court.

Dr. Siddhpura reported achieving several positive outcomes based on the results of his report. These effects included Adam Smith avoiding jail time, the potential for the information and research to be published in the near future, and the judge criticizing the New South Wales government for their unreasonable gun laws.

Acting District Court Judge Paul Conlon found Adam Smith guilty of firearms charges under the technicalities of the law but expressed his dissatisfaction with the charges related to possession of gel-blaster toys. In an article in the guns and hunting magazine, Sporting Shooters, Judge Conlon criticized gun laws that classify children’s toys as firearms as “nothing short of a disgrace.”

Regarding what he learned as an engineer and citizen from this case, Dr. Siddhpura stated, “I believe there are numerous areas in society and government that have significant knowledge gaps or issues that can be resolved with the assistance of engineering experts.”

After serving as an engineering expert witness in this case, Dr. Siddhpura realized that there is a whole new world outside of the traditional engineering domain that requires the tremendous help of engineers.


The case has had a turn since we published this article about a week ago. Upon reviewing the substantive findings presented to the court by EIT’s Dr. Milind Siddhpura in his in-depth 15-page analysis, Adam Smith has been exonerated of all charges.

Acting District Court Judge Paul Conlon has asked the police/government to change the law to create a separate category for the ‘Toy Guns’ per Dr. Siddhpra’s recommendations. “Having concluded the formal part of my judgment, this issue of gel blasters would seem to be ripe for parliament to be more specific regarding the prohibition of such items,” said Judge Conlon.

Patently absurd nonsense: Judge furious over NSW guns laws, police actions
The Professional Engineer as an Expert Witness:
Engineers as Expert Witnesses and Advisers:

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