This AI system is temporarily under construction, please excuse our mess. The responses provided are not legal advice, and users must independently verify all information.
Login Upgrade About Treatise

Defining Logical Relevance

G. Alexander Nunn, Defining Logical Relevance in Nunn on Evidence (2025), available at https://nunn.law/defining-logical-relevance. | View history

This initial step in determining whether a piece of evidence can even be considered for admission in a trial is fundamental. We are concerned here with a very basic, yet critically important, question: Does this piece of information have any tendency to make a fact that matters in this case more or less likely to be true than it would be if we didn’t have this information? Think of it as the gatekeeper at the very entrance of the courtroom. Before evidence can be scrutinized for other potential issues, it must first pass this initial, and quite liberal, test of logical connection.

At its heart, logical relevance is about the relationship between an offered item of evidence and a proposition that we are trying to prove or disprove. It’s not about whether the evidence definitively proves something, or even whether it makes that thing highly probable. Instead, the standard is far more accommodating. We are looking for any tendency, however slight, to nudge our understanding of a particular fact one way or the other.

Key Overview

The core principle of logical relevance, or probativeness, is deceptively simple: evidence is relevant if it has any tendency to make a fact more or less probable than it would be without the evidence. This “tendency” test sets a minimal threshold. The evidence doesn’t need to be a smoking gun; it doesn’t need to single-handedly convince the trier of fact. It merely needs to be a single brick in the wall of proof, even if that brick is a small one. The law’s definition of relevance is intentionally broad, reflecting a preference for admitting evidence that could rationally influence the fact-finder.

Imagine a see-saw. A fact is on one side. We introduce a piece of evidence. Does that evidence, even if only by a feather’s weight, tip the see-saw, however slightly, towards “more probable” or “less probable”? If it does, it has met the basic standard of probativeness. The key here is the incremental effect on probability. This liberal standard means that evidence will only be excluded for lack of relevance if it is utterly incapable of affecting the probability of the fact in question. The mere possibility that the evidence could influence the trier of fact, even by a small margin, is generally enough to satisfy this initial hurdle.

This low bar signifies that, at this stage, we are not assessing the weight or persuasiveness of the evidence. That is a separate question for the fact-finder – the jury or, in a bench trial, the judge – to consider later. Our concern here is purely about the logical connection. Is there some rational link? If so, the evidence is deemed probative. It is either relevant or it isn’t; the concept of “degrees” of relevance isn’t part of this initial assessment.

The Nature of the “Tendency” Test

The “tendency” required for a piece of evidence to be deemed logically relevant is a matter of logic and experience, rather than a strict legal formula. The law doesn’t hand us a pre-defined list of what makes evidence relevant in every conceivable situation. Instead, it directs us to use our common-sense reasoning, our understanding of how the world generally works, and the principles of logical inference. When we ask if evidence has a tendency to make a fact more or less probable, we are essentially asking if there is a rational, inferential connection between the two.

This reliance on common-sense reasoning means that the assessment of relevance often involves looking beyond formal legal rules to broader principles of human experience and logic. Think about the kind of reasoning you use every day to draw conclusions. If you see someone come inside with a wet umbrella and raincoat, you infer it’s likely raining outside. That inference isn’t based on a legal statute; it’s based on your experience and logical deduction. Similarly, in the courtroom, a lawyer might offer evidence of skid marks at an accident scene. Common sense tells us that long skid marks tend to suggest that a vehicle was traveling at a significant speed or braked suddenly. This doesn’t conclusively prove high speed, as there could be other explanations (e.g., an oil slick on the road, faulty brakes), but it makes the proposition of high speed slightly more probable than it would be if there were no skid marks at all.

The inferential chain between the evidence and the fact to be proved can be direct or indirect, simple or complex. The evidence might support an inference that, in turn, supports another inference, which ultimately relates to the fact in question. As long as each link in this chain is rational and based on common experience or logic, the evidence can satisfy the tendency test. The law tacitly refers to logic and general experience when determining relevance. Judges must often draw upon background beliefs and generalizations that are widely accepted. If a piece of evidence is so ambiguous or its connection to the fact so attenuated that it could not rationally affect a person’s assessment of the fact’s probability, then it is deemed irrelevant.

It’s crucial to understand that this standard does not demand certainty or even a high degree of probability. The evidence merely needs to “help a little” in the fact-finder’s task of determining the likelihood of a fact. The assessment is qualitative, not quantitative at this stage. We are not asking how much more or less probable the fact becomes, only whether its probability is affected at all. This is a deliberately permissive standard, designed to ensure that the trier of fact has access to all information that could rationally bear on its decision-making process, unless excluded for other reasons we will discuss in later sections. The process involves considering whether, based on principles evolved from experience or science and applied logically to the specific situation, the evidence tends to prove the matter sought to be proved.

Sources

Buy Me A Coffee
Enjoying nunn.ai? Buy me a coffee!
Terms of Service | Privacy Policy | Questions? Comments? Contact alex@nunn.ai | © 2025 Nunn Ventures, LLC. All rights reserved.
Upgrade to PRO