The admissibility and persuasiveness of expert evidence

• Published date: 01 October 2023
• Author: Thomas Altobelli,Bruce Gordon Smith
• Date: 01 October 2023
• DOI: http://doi.org/10.1111/fcre.12748

SPECIAL ISSUE ARTICLE

The admissibility and persuasiveness

of expert evidence

Thomas Altobelli

1

|Bruce Gordon Smith

2

1

Federal Circuit and Family Court of Australia,

Sydney, New South Wales, Australia

2

Federal Circuit and Family Court of Australia,

Newcastle, New South Wales, Australia

Correspondence

Thomas Altobelli, Federal Circuit and Family

Court of Australia, 97-99 Goulburn Street,

Sydney, NSW, Australia.

Email: associate.justicealtobelli@fcfcoa.gov.au

Abstract

Parenting plan evaluators are expert witnesses who offer

their opinion. Courts in common law jurisdictions generally

do not accept evidence of an opinion as it is not considered

to be reliable evidence from which to establish a fact. An

exception to that general principle is expert opinion evi-

dence. In short, an opinion from a person with specialized

knowledge or expertise about the area in which they are an

expert may be sufficiently reliable to form an evidentiary

basis from which to make a finding of fact, provided the

opinion meets certain criteria. These criteria will be dis-

cussed in this article, as well as what is relevant, reliable and

persuasive evidence. The relevant legal principles will be

examined in an historical and contemporary, theoretical and

practical context. The authors reflect on their considerable

experience as consumers of expert evidence and apply this

to parenting plan evaluations, as well as considering future

challenges in the field.

KEYWORDS

expert evidence; future challenges; parenting plan evaluations;

practical thoughts on writing parenting plan evaluations; relevant,

reliable and persuasive evidence

Key points for the family court community

•As a parenting plan evaluator you need a basic under-

standing of the rules of evidence to write an admissible

report.

DOI: 10.1111/fcre.12748

© 2023 Association of Family and Conciliation Courts.

832 Family Court Rev. 2023;61:832–853.

wileyonlinelibrary.com/journal/fcre

•If your parenting plan evaluation is written with these

rules in mind it is more likely to be persuasive to a Court.

•When you understand the purpose of the rules it is

easier to follow them and to write better reports.

•There are some rules which are specific to each jurisdic-

tion and you should always ask for guidance, especially

when starting out.

•There are many future challenges confronting parenting

plan evaluators and the Courts in relation to parenting

plan evaluations.

INTRODUCTION

Parenting plan evaluators are expert witnesses who offer their opinion.

1

Courts in common law jurisdictions

generally do not accept evidence of an opinion as it is not considered to be reliable evidence from which to establish

a fact. An exception to that general principle is expert opinion evidence.

While the specifics vary from jurisdiction to jurisdiction, the laws about expert evidence

2

and their judicial inter-

pretations

3

tend to be similar. In short, an opinion from a person with specialized knowledge or expertise about the

area in which they are an expert, may be sufficiently reliable to form an evidentiary basis to make a finding of fact,

provided the opinion meets certain criteria. These criteria will be discussed in this article.

What is evidence? A definition of the fundamental legal concept of evidence is often absent from the most obvious

places such as enacted laws. For present purposes we adopt the following working description of evidence: evidence is

any information, or objects, which the laws of evidence allow a judge to take into account in making their decision.

The Federal Rules of Evidence (United States of America) (FED.R.EVID. 410) state that relevant evidence is

admissible, but irrelevant evidence is not admissible.

4

The authors' experience is that relevance is often difficult to

determine at the beginning of the case, especially a case about children, as the issues that need to be decided often

evolve during the course of the trial. As the issues evolve, so too does the concept of relevant evidence.

However, relevant evidence may not be reliable. Reliability means that the trial judge can safely depend on the evi-

dence because of its quality and trustworthiness. The evidence may not be reliable in the context of a particular case (e.g., it

is not sufficiently related to the issue to be decided), or it might not be reliable generally (e.g., it is notoriously discredited).

Even if evidence is both relevant and reliable, a trial judge might not place much weight on that evidence. The

weight a trial judge applies to any evidence is an exercise of discretion having regard to all other evidence in

1

Arnold T. Shienvold ET AL., Guidelines for Parenting Plan Evaluations in Family Law Cases,ASS'NOF FAM.AND CONCILIATION COURTS,https://www.afccnet.org/

Portals/0/Committees/2022%20Parenting%20Plan%20Guidelines.pdf?ver=pL0FdZapJmsbfUvQ6zzN-A%3D%3D (The Foreword to the AFCC Guidelines

for Parenting Plan Evaluations in Family Law Cases states: “The term Child Custody Evaluations has been replaced with Parenting Plan Evaluations. This

reflects an important shift away from the term “child custody,”which connotes possession and control of children rather than responsibility for their care.

Child Custody Evaluations, Parental Responsibilities Evaluations, Best Interest Evaluations, Custody and Access Evaluations, Parenting Time Evaluations, or

similar terms are used in various jurisdictions.”We have adopted the term parenting plan evaluations in this article, and refer simply to evaluators.)

2

FED.R.EVID. 702 (is titled “Testimony by Expert Witnesses”and deals with opinions of witnesses “qualified as an expert by knowledge, skill, experience,

training, or education”.); See Evidence Act 1995 s 79 (Austl.). (is titled “Exception: opinions based on specialized knowledge”and deals with opinions “based

on the person's training, study or experience”.).

3

Compare Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993)., and Gen. Elec. Co. v. Joiner 522 U.S. 136 (1997)., and Kumho Tire Co. v. Carmichael,

526 U.S. 137 (1999)., and Frye v. United States, 293 F. 1013 (D.C. Cir. 1923). (and previously in the United States of America and still in many state courts),

with Dasreef Pty Ltd v Hawchar (2011) 243 CLR 588 (Austl.). (in Australia compare for example), and Makita (Australia) Pty Ltd v Sprowles (2001) 52 NSWLR

705 (Austl.). (in Australia compare for example).

4

See Evidence Act 1995 ss 55, 56 (Austl.). (similar provision contained in sections 55 and 56).

ALTOBELLI and SMITH833