The statement is intended to become evidence before a Court.
It is also certified by a notary or lawyer or some other judicial officer that can administer oaths, to the effect that the person signing the affidavit was under oath when doing so (as is shown on the bottom of the sample affidavit form pictured left).
These documents carry great weight in Courts to the extent that judges have been known to (albeit rarely) accept an affidavit instead of the testimony of the witness.
But, as Justice Fraser said in Pierre v Lil'Wat Nation 1999 61 BCLR 3d 381:
"Baron Bowen once sardonically remarked, 'Truth will out, even in an affidavit', reflecting the universal understanding of those with courtroom experience that the affidavit is an effete vehicle, when compared with oral testimony in court, for the proper determination of factual disputes."
An affidavit can even bring evidence to the Court in spite of the deponent's death before trial.
In Leclerc v St. Louis, 11 DLR 4th 765, a 1985 and 2-1 split Ontario court of appeal decision, this was the issue before the Court.
In citing other, older and some British decisions, the judge said:
"An affidavit given on an interlocutory motion was received into evidence at trial where the deponent had died prior to trial even though he had not been cross-examined. The evidence of (a) defendant taken on a reference, who had died prior to cross-examination, was admissible."
"I do not reach my decision without some hesitation because certain paragraphs in the affidavit appear to contain inadmissible evidence.
"It must be remembered that the application was to have the affidavit received in evidence. It was not to have the contents accepted by the court.
"The affidavit would not tie the trial judge's hands. It will be up to him to sort out what constitutes properly admissible evidence and what should be rejected. Should he decide to accept parts of the affidavit, it will still be up to him to decide what weight that evidence should be given."
See also Affidavits: The How-To Guide