What Is Evidence?

August 4, 2026
10:00 am

What Is Evidence?

August 4, 2026

We have written before about the need for evidence to win your case in court. That article focused specifically on using expert evidence to prove damages.

We have also written specific articles on other aspects of evidence, including:

THE BASIC QUESTION

What we have not done to date is answered the basic question “what is evidence?”

THE IMPORTANT QUESTION

Why is it important to understand what evidence is?

UNDERSTANDING IS IMPORTANT

Understanding the results of legal cases starts with understanding that cases are decided on the evidence before the court. A common saying in law is that legal decisions are based 10% on the law and 90% on the facts.

This helps you:

appreciate that the result of the case is sometimes decided by the evidence, which is missing, not just the evidence that is presented.
which emphasizes the importance of gathering evidence if you are the party to a case, and
understand the importance of your role, if you are called as a witness, or asked to supply documents as evidence, and also
understand why sometimes decisions might seem surprising, unless you pay close attention to the facts decided by the judge, which
are based on the evidence presented:
- which might not be obvious or common knowledge, and
- sometimes, things that “common knowledge” knows or believes to be facts are not part of the evidence proven in the specific case, and thus, not part of the basis of the decision.

A COMMON DEFINITION

The Merriam -Webster dictionary defines “evidence” first as “an outward sign,” giving the example “evidence of an early spring.”

The second definition listed is “something that furnishes proof,” but gives another example from outside law, namely “There’s no evidence that these devices actually work.”

It is not until the fourth listed definition that we get to something specific to law, which provides two possibilities:

“something (as testimony, a writing, or an object) submitted at a judicial or administrative proceeding for the purpose of proving a party’s case” or
“the collection of proof submitted at a judicial or administrative proceeding.”

THE LEGAL CONCEPT OF EVIDENCE

“[S]omething … submitted at a judicial or administrative proceeding…” comes will help you understand what lawyers and judges mean when we talk about “evidence.”

However, in court, or in an administrative decision, “evidence” does not exist in a vacuum. To know what evidence is necessary in a particular case, we need to focus on the last phrase of that definition:

“for the purpose of proving a party’s case”

How do we know what is necessary to prove a case?

To understand this, you need to understand the essential elements , or facts, which make up the test for the specific case to be proven, whether a criminal charge or a civil or family law cause of action.

Information that tends to prove, or disprove, a part of that test is called relevant. Only relevant information is properly received as evidence.

Cases are won or lost based on the presence or absence of relevant evidence.

What makes something relevant?

There are two aspects of relevance:

Factual relevance
Legal relevance

Factual relevance refers to whether the information put forward as potential evidence helps show whether or not the fact trying to be proved is more or less likely, as a matter of logic. Most people understand this concept.

Legal relevance is more difficult. Evidence which is legally relevant is sometimes referred to as material evidence. It limits relevant evidence to those facts that are necessary to prove or disprove an issue in the specific case.

Only material evidence is admitted in court, or at an administrative tribunal. So, it is important to know what is NOT material, to present your case clearly.

UNDERSTANDING EVIDENCE IS THE KEY TO A WINNING CASE

You want to present ALL the available material evidence to prove your case or disprove your opponent’s case.

It requires knowledge of the law that applies in a particular situation. We have written before about the importance of understanding the issues for the purposes of drafting pleadings that accurately describe your case, but it is just as important for assembling and presenting the evidence to prove that case.

A deceptively simple example is the law of negligence. To an average person, “negligence” might mean simply reckless behaviour. But in law, the elements of negligence are:

A duty of care to prevent foreseeable harm to persons like the Plaintiff.
A breach of that duty of care
Which causes foreseeable harm to the Plaintiff?
And causes provable damage to the Plaintiff.

Do not prove any of these, and your case fails. So, even if there are dead flies in your bottled water, you may not have a claim even if it caused you actual psychiatric harm, if you cannot prove that a person “of ordinary fortitude” would suffer an injury from seeing the flies in the bottle of water. That would require evidence, probably from a medical expert. Knowing the necessary questions is part of the art of preparation of a case.