(Un-)Interpretability in Expert Evidence: An Inquiry into the Frontiers of Evidential Assessment

• Author: Alex Biedermann & Kyriakos N. Kotsoglou
• Pages: 483-517

Quaestio facti. Revista Internacional sobre Razonamiento Probatorio / International Journal on Evidential Legal Reasoning

Año 2022 N. 3 pp. 483-517 DOI: 10.33115/udg_bib/qf.i3.22599

Quaestio facti. Revista Internacional sobre Razonamiento Probatorio

Quaestio facti. International Journal on Evidential Legal Reasoning

Sección: Science for Legal Proceedings

N. 3 | 2022 pp. 483-517

Madrid, 2022

DOI: 10.33115/udg_bib/qf.i3.22599

© Marcial Pons Ediciones Jurídicas y Sociales

© Alex Biedermann

© Kyriakos N. Kotsoglou

ISSN: 2604-6202

Recibido: 06/03/2021 | Aceptado: 02/07/2021 | Publicado: 03/11/2021

Editado bajo licencia Reconocimiento 4.0 Internacional de Creative Commons

(UN-)INTERPRETABILITY IN EXPERT EVIDENCE:

AN INQUIRY INTO THE FRONTIERS

OF EVIDENTIAL ASSESSMENT

Alex Biedermann*

Kyriakos N. Kotsoglou**

ABSTRACT: Evidence law regimes across several contemporary legal orders provide a host of doctrinal

devices designed to probe various sorts and sources of information, especially with respect to their

accuracy and reliability. ese legal provisions, however, are vulnerable to or even tolerant towards

uninterpretable evidence, that is evidence whose probative value cannot be assessed. is article

critically examines and discusses the «littering paths» of uninterpretable evidence in legal proceed-

ings. We point out the misinformative character of such evidence as well as the potentially mis-

leading impact on criminal adjudication when using scientic evidence for purposes that, strictly

speaking, the evidence cannot help with. We identify common causes and possible remedies and

argue that to track uninterpretability, it is necessary to understand what exactly it means to say

that a piece of evidence is probative in the procedural space of reasons, and how to draw the line

between informative and non-informative items of evidence.

KEYWORDS: scientic evidence, interpretability, probative value, propositions, forensic science

* University of Lausanne, Faculty of Law, Criminal Justice and Public Administration, School of

Criminal Justice, 1015 Lausanne-Dorigny (Switzerland). e authors gratefully acknowledge the sup-

port of the Swiss National Science Foundation through grant BSSGI0_155809, the Fondation pour

l’Université de Lausanne and the Société Académique Vaudoise. – alex.biedermann@unil.ch

** Northumbria University, Faculty of Law & Business, Newcastle Upon Tyne, NE1 8ST (UK). –

kyriakos.kotsoglou@northumbria.ac.uk

484 ALEX BIEDERMANN  KYRIAKOS N. KOTSOGLOU

Quaestio facti. Revista Internacional sobre Razonamiento Probatorio / International Journal on Evidential Legal Reasoning

Año 2022 N. 3 pp. 483-517 DOI: 10.33115/udg_bib/qf.i3.22599

SUMMARY: 1. INTRODUCTION. 1.1. Seemingly probative scientic evidence? 1.2. Aims and

scope.—2. THEORISING (UN-)INTERPRETABILITY OF SCIENTIFIC EVIDENCE. 2.1

Delimiting the scope of inquiry: the model-based view of interpretation. 2.2. Principles of sci-

entic interpretation. 2.3. Role, limitations and necessity of empirical measures of scrutiny for

forensic science evidence. 2.4. Uninterpretability: conceptualising the frontiers of interpretability.

2.5. Distinguishing (un-)interpretability from probative value and relevance. 2.6. (Un-)interpreta-

bility vs. inconclusiveness.—3. PROBING FOR (UN-)INTERPRETABILITY. 3.1. Distinguish-

ing between evaluative, investigative and technical reporting. 3.2. Uninterpreted and partially

interpreted vs. uninterpretable evidence. 3.3. e central role of main objects of litigation and

propositions in interpretation. 3.4. Exemplifying (un-)interpretability: probabilistic genotyping.

—4. CONCLUSIONS

RECOMMENDED CITATION: ALEX BIEDERMANN; KYRIAKOS N. KOTSOGLOU, 2021:

«(Un-)interpretability in expert evidence: an inquiry into the frontiers of evidential assessment»,

in Quaestio facti, 3: 483-517. Madrid: Marcial Pons Ediciones Jurídicas y Sociales. DOI: http://

dx.doi.org/10.33115/udg_bib/qf.i3.22599

1. INTRODUCTION

1.1. Seemingly probative scientic evidence?

It is not an exaggeration to say that the eld of evidence & proof has primari-

ly focused—at least for the past few decades—on the reliability of various forensic

science 1 disciplines. From the ground-breaking Frye 2 decision which set the initial

standards for scientic validity in the 1920s, widely considered even beyond the

American context, over the «DNA wars» of the 1990s 3 to the ongoing discussions

over how to dene criteria of scientic validity, 4 scholars, criminal courts and sci-

entic organisations have tried to lay down the procedural and methodological ar-

chitecture for the operation of forensic practitioners in the criminal justice system.

ese developments raise the question of what else could and, indeed, should

have been discussed, in addition to reliability. As we will argue below, the main and

usually sole requirement for admissibility in criminal proceedings is a core feature

of forensic scientists’ operations that, so far, is not adequately illuminated. Whereas

reliability—based on «validity» in the US 5 and «suciently reliable scientic basis»

1 For the purpose of this paper, forensic science is broadly understood as «the application of scien-

tic or technical practices to the recognition, collection, analysis and interpretation of evidence for

criminal and civil law or regulatory issues». See P’ C  A  S 

T (PCAST), 2016: 1, hereinafter cited as PCAST Report, and PCAST as council.

2 Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).

3 See A, 2007.

4 See the PCAST Report for an example of a report that stirred considerable debate in recent years.

5 Daubert v. Merrell Dow Pharm., Inc. (509 U.S. 579 [1993]). e Daubert standard is the test

currently used on the federal level and in several jurisdictions on the state level. In the federal court

UNINTERPRETABILITY IN EXPERT EVIDENCE… 485

Quaestio facti. Revista Internacional sobre Razonamiento Probatorio / International Journal on Evidential Legal Reasoning

Año 2022 N. 3 pp. 483-517 DOI: 10.33115/udg_bib/qf.i3.22599

in England and Wales 6—invokes the exception to the opinion rule which raises a

general ban on opinions from any other person than the triers of fact, relevance is the

main requirement for admissibility, save for any exclusionary rules.

Relevance too seems to be a straightforward topic insofar as it describes a rela-

tionship between two facts. A fact x is relevant to a fact y when the former has some

material bearing on the latter. For example, to ascribe criminal liability to or acquit a

defendant, we need evidence which is capable of helping to prove or disprove some

element of the respective criminal allegation. is is obviously easier said than done.

Admitting relevant evidence at trial and excluding irrelevant evidence is similar to

the ctional rugby manager’s instruction «To win, you need to score more tries than

the other side». An expected response to that can only be: «Sure, but how?» 7

In common law, James Fitzjames Stephen’s classical denition seems to oer a

helpful approach to criminal courts: «e word “relevant” means that any two facts

to which it is applied are so related to each other that according to the common

course of events on either taken by itself or in connection with other facts proves

or renders probable the past, present or future existence or non-existence of the

other». 8 Explicit reference to the term «probability» in the above denition has been

replicated in modern legislature, most notably in FRE 401 (US) according to which

«Evidence is relevant if (a) it has any tendency to make a fact more or less probable

that it would be without the evidence; and (b) the fact is of consequence in deter-

mining the action». Similarly, in England and Wales Lord Simon of Glaisdale noted

that «Evidence is relevant if it is logically probative or disprobative of some matter

which requires proof […] It is sucient to say […] that relevant (i.e. logically pro-

bative or disprobative) evidence is evidence which makes the matter which requires

proof more or less probable». 9

But before the critical reader is led to think that judges and jury in criminal trials

deploy any sort of probability calculus to determine relevance and weight, 10 it is

worth reminding one of the core elements in Stephen’s denition. What is neces-

sary, according to the abovementioned determination, is a vast array of background

generalisations about the world, contextual information and, often, cultural under-

standing in order to place the evidence into context. e law predicates admissibility

on relevance, but as ayer put it, «the law furnishes no test for relevance». 11 It is

system, it replaced the Frye standard, which, nota bene, is still used in some states.

6 R v Dlugosz [2013] EWCA Crim 2.

7 See W, 1995: 239.

8 S, 1948: art. 1.

9 DPP v Kilbourne [1973] A.C. 729 at 756 HL.

10 See R v Adams [1996] 2 Cr App R 467, 481, 482 (England and Wales), where the Court of Ap-

peal remarked that to «introduce Bayes’ eorem, or any similar method, into a criminal trial plunges

the jury into appropriate and unnecessary realms of theory and complexity deecting them from their

proper task».

11 T, 1898: 265.