Short answer. Testimony must be limited to personal knowledge. Rule 130, Section 22 provides that a witness can testify only to facts within his or her personal knowledge — facts derived from his or her own perception. Secondhand accounts of what someone else observed generally fall outside what the witness may competently testify to.
What the law says
A witness can testify only to those facts which he or she knows of his or her personal knowledge; that is, which are derived from his or her own perception.
Rule 130, Section 22 — Testimony confined to personal knowledge. Read the full provision →
The personal knowledge requirement
Section 22 grounds a witness's competence to testify in personal knowledge — facts the witness knows because they came from his or her own perception. This is the foundational limitation underlying the broader rule against hearsay: a witness is a source of firsthand information, not a conduit for secondhand accounts. This requirement is the doctrinal foundation for the rule against hearsay, which generally bars secondhand statements offered to prove the truth of what they assert. Understanding this baseline requirement makes the hearsay rule's later exceptions easier to follow, since each exception carves out a narrow situation where the ordinary personal-knowledge concern is considered less pressing.
What 'own perception' means
The rule directly ties knowledge to the witness's own senses — what he or she personally saw, heard, or otherwise directly perceived. A witness relaying what another person told them about an event, rather than what the witness perceived themselves, does not satisfy this personal-knowledge standard for that particular fact being offered. Sight and hearing are the most common examples, but the rule extends to any of the witness's own five senses that directly registered the fact in question.
Why this matters when preparing testimony
Before offering a witness to establish a fact, it is worth checking whether that witness actually perceived the fact directly, or is merely repeating what someone else observed or said. Section 22 is the basic gatekeeping requirement that determines whether the witness can competently testify to that fact at all. Courts and counsel alike closely scrutinize whether a proposed witness genuinely perceived the fact firsthand, since testimony that fails this threshold can be excluded outright regardless of how relevant or persuasive it otherwise seems.
Who the requirement binds and what breaks it
The requirement binds every witness offering testimony to prove a fact, whether called by the plaintiff, the defendant, or the prosecution — there is no category of witness exempt from it. A breach is not a mere irregularity; testimony offered on secondhand knowledge is generally inadmissible for the fact it purports to establish, and an objection on that ground, timely raised, can keep it out entirely or have it stricken if it slips in unchallenged. The requirement does not bar a witness from recounting that a statement was made — only from using it to prove the truth of what the statement asserted, since that inferential leap is exactly what personal knowledge is meant to guard against.