If you plan to use your genealogical research to support a legal claim in Canada, you should have a basic understanding of some of the legal principles of evidence. However, please keep in mind that this is a new field. Until recently, genealogical evidence was almost never required by the Canadian government. So, even legal experts aren’t clear about how these principles will be applied. History is still being made.

Best evidence rule

Canadian common law is based on British common law, in which one of the basic rules is that the “best evidence” is always necessary. This means that if there is more than one way to demonstrate a fact, you need to use the stronger method. For example, documentary evidence of a marriage (such as a government marriage certificate) might be the best evidence available to prove a marriage. But, if a witness to the wedding is still alive, the best evidence is the testimony of the witness.
The “best evidence” rule also means that if you’re using a document as evidence, and the original is available, generally you can’t use a copy. Exceptions can be made if the original can’t be removed from its location for logistical or legal reasons. If a copy is used, the person who made the copy, a witness who was present when the copy was made or a custodian of the records needs to testify that it is a perfect copy. If the original has been destroyed or lost, a copy can be admitted, but again, you need to offer proof that the original was destroyed or lost. You can also use a copy if the original is in the possession of an opponent or someone who refuses to produce it and cannot be forced to do so.

Documentary evidence

To types of evidence are important to genealogists: documentary and oral history. Both are considered hearsay by courts, so they have special guidelines for admissibility as exceptions to the hearsay rule. In general, the principles involved (for both cases) are: necessity and trustworthiness.
The first exception for documents is for “public documents”. To be considered a public document, it has to be:
about a public subject
created by public officials (or private citizens who have specific public duties, such as officers of the Hudson’s Bay Company ) whose job it is to gather and record information
meant to be kept as a permanent record, and
available to the public for inspection.
A public document, and the statements made within it, is admissible because it is necessary to avoid undue disruption of government. It is considered trustworthy because our society has confidence in its public officers, “presuming they will discharge their official duties accurately and faithfully,” and because the record is available for public scrutiny and thus has had the opportunity to be challenged.
Examples of public documents include: birth, marriage, and death registers; certificates prepared from such registers; government ship journals; and official government surveys, maps and plans.
Business records are also admissible, as long as they meet these conditions:
The person who created them had a duty to gather and record the information.
The record was created at the time of the event.
The person who created them had personal knowledge of the facts.
The person who created them had no motive to misrepresent the facts.
This is another example where Hudson’s Bay Company records would be acceptable.
Non-public documents must be “authenticated” before they can be used in court. This means that if the author or witness to the creation of the document is available, he or she can testify that the document is “real” (not a forgery or fake).  
There are special rules that permit wills to be used in court without the witnesses having to testify.
Ancient documents can be used in court without “authentication” under certain conditions:
The document is over 30 years old (in some provinces, 20 years).
The document came from “proper custody.”
There are no special reasons to distrust it.
Generally, an old document can be used if it is necessary, because no other evidence is available, and if it is it judged to be reliable. To be considered reliable, the person who wrote it has to have been competent, have personal knowledge of the facts, not have any reason to lie, and have written the document before there was any controversy.
Examples of the kinds of records that have been admitted to Canadian courts under the “ancient documents” exception are: reports of Hudson’s Bay agents and the diaries of early clerks, traders and explorers.
Proper custody means that the records were created and stored by the appropriate authorities, so it’s unlikely that anyone had the opportunity for forgery.
An “ancient document” can’t be used if there is proof that the people who created it were biased.
In addition, the courts have indicated that the following conditions must be met:
“The circumstances are such that a sincere and accurate statement would naturally be uttered, and no plan of falsification be formed.”
“Even though a desire to falsify might present itself, other considerations such as the danger of easy detection or the fear of punishment would probably counteract its force.”
“The statement was made under such conditions of publicity that an error, if it had occurred, would probably have been detected and corrected.”

Some legal writers have suggested that it is unclear whether these same rules will apply in Aboriginal rights cases or whether they will be relaxed somewhat: “Whether this new dispensation also means that in Aboriginal litigation involving ancient documents the traditional hallmarks of reliability will be ignored is also an open question.”

Oral history evidence

The general principles for admission of oral history evidence are the same as for documents: necessity and reliability. In the case of a culture that did not write its stories down (such as Canadian Aboriginal people in the distant past), clearly necessity is covered. Reliability must be considered on a case-by-case basis. Oral history evidence has been admitted and treated as reliable in Aboriginal rights cases where there are special circumstances. For example, in the case of Delgamuukw v. B.C. it was argued that oral history was passed down at public gatherings where it was witnessed and thus publicly affirmed.
In an order in Tsilhqot’in Nation v. British Columbia, the judge seems to have begun the process of developing a practical approach to dealing with oral history evidence.
The judge said that at the beginning of the trial, he would like the lawyers to give him general information about the oral history traditions of the people they represent. He would want to know:
How the people generally preserve their oral history