The nature of questions arising in court that can be addressed via probability and logic Bernard Robertson bwnremail@gmail.com

(NZ) Evidence Act 2006 Purpose The purpose of this Act is to help secure the just determination of proceedings by— (a) providing for facts to be established by the application of logical rules; and (b) providing rules of evidence that recognise the importance of the rights affirmed by the New Zealand Bill of Rights Act 1990; and (c) promoting fairness to parties and witnesses; and (d) protecting rights of confidentiality and other important public interests; and (e) avoiding unjustifiable expense and delay; and (f) enhancing access to the law of evidence.

US Federal Rules of Evidence Rule 102. Purpose These rules should be construed so as to administer every proceeding fairly, eliminate unjustifiable expense and delay, and promote the development of evidence law, to the end of ascertaining the truth and securing a just determination.

Truth-finding Determination of what occurred in the past Protect public from crime protect individuals from government intervention

Truth now v long run accuracy Legal professional privilege

Truth finding v other values Exclusion of evidence illegally obtained (but still has to be established to some standard that the evidence was illegally obtained: Q of fact and of law)

Evidence Act (NT) S 97(1) Evidence of . . . conduct of a person . . .is not admissible to prove that a person had a tendency . . . to act in a particular way . . . unless: (b) the court thinks that the evidence will . . . have significant probative value.

Evidence Act (NT) Judge must decide whether “significant probative value” probative value is usually matter for jury

Relevance/probative value Probative value measured by LR Relevance means LR ≠ 1 (but see IMM [96] per Gageler J)

Evidence Act 2006 NZ Evidence is relevant in a proceeding if it has a tendency to prove or disprove anything that is of consequence to the determination of the proceeding. “probative value” not defined

U S Federal Rules of Evidence 401 - Evidence is relevant if: it has any tendency to make a fact more or less probable than it would be without the evidence; and the fact is of consequence in determining the action. Probative value not defined

Kilbourne v DPP Evidence is relevant if it is logically probative or disprobative of some matter which requires proof . . relevant (ie. logically probative or disprobative) evidence is evidence which makes the matter which requires proof more or less probable.

NT/Australian Act Relevant = evidence that, if it were accepted, could rationally affect … the assessment of probability of the existence of a fact in issue … Probative value = “extent to which the evidence could rationally affect the assessment of probability of the existence of a fact in issue”

IMM v R [2016] HCA 14 Are these different? Should “if it were accepted” be read into definition of probative value? Yes – evidence must be accepted to be of any probative value No – different questions for judge See IMM at [140]

Dingo Baby case “It is an obvious proposition of logic that you cannot be satisfied beyond reasonable doubt of the truth of an inference drawn from facts about the existence of which you are in doubt” See IMM at [98] per Gageler J

R v Shepherd “playing that game, anything which was the subject of evidence could be reduced to a level at which the jury could be said to be satisfied beyond reasonable doubt, even if it be at as basic a level as that the witness said what is recorded in the transcript”

IMM v Queen [2016] HCA 14 IMM charged with indecency and sexual intercourse with step-grandchild from age 4 – 12. Contested evidence: complainant alleged that when she and friend had given IMM a back massage, he ran hand up her leg.

IMM v Queen Evidence admitted to show IMM had sexual interest in complainant Judge assessed probative value of the evidence on “assumption that jury would accept the evidence”.

IMM v Queen What matters is judge to take into account? Should judge assume jury will “accept the evidence”? What is the “evidence”?

IMM v Queen H1 = accused did criminal acts alleged H2 = accused did not do criminal acts alleged W = witness states accused ran hand up leg E = accused ran hand up leg

IMM v Queen Which LR must have “significant pv”? P(E|H1)/P(E|H2) P(W|E)/P(W|~E) P(W|H1)/P(W|H2)

IMM v Queen “assuming jury would accept evidence” must refer to P(E|H1)/P(E|H2)

IMM v Queen but s 97(1) refers to admissibility of: “evidence of the … conduct of a person …” The evidence of the conduct is W? The evidence that must be admissible is W?

IMM v Queen So LR of concern is P(W|E)/P(W|~E) Or P(W|H1)/P(W|H2)

IMM v Queen P(W|I) = P(W|H1, E, I) P(H1, E|I) + P(W|H1, ~E, I) P(H1, ~E|I) + P(W|H2, E, I) P(H2, E|I) + P(W|H2, ~E, I) P(H2, ~E|I)

P(W|H1, E, I) = 1? P(W|H1, ~E, I) = ? gilding the lilly P(W|H2, E, I) = 1? given charges + P(W|H2, ~E, I) = complete set up

P(W|H1, ~E, I) P(W|H2, ~E, I) clearly depend on credibility of witness/complainant

Relevance/probative value Statutory definition of relevance focuses on content of the evidence P(E|H1)/P(E|H2) “Probative value” is P(W|H1)/P(W|H2)

Relevance/Probative value Central issue is definition of “evidence” Point missed in discussion of “if accepted” Relevance: Judge must consider P(E|H1) etc Probative value: requires P(W|H1) etc

Scientific evidence Witness purports to give identification H1 = accused was source of trace H2 = accused was not source of trace W = witness states accused was source of trace E = comparison of trace and accused’s sample

Other issues Does extrinsic evidence of correctness of identification make identification stronger? Should proof that a confession is true make it admissible if circumstances likely to render confession unreliable? What if confession reveals location of previously unfound body etc?

Answer to question of the week Any question that is (i) related to determining the truth and (ii) does not require balancing truth-determination with any other value.