Notes of Advisory Committee on Rules

"[T]he rule requiring that a witness who testifies to a fact which can be perceived by the senses must have had an opportunity to observe, and must have actually observed the fact" is a "most prevasive manifestation" of the common law insistence upon "the most reliable sources of information." McCormick § 10, p. 19. These foundation requirements may, of course, be furnished by the testimony of the witness himself; hence personal knowledge is not an absolute but may consist of what the witness thinks he knows from personal perception. 2 Wigmore § 650. It will be observed that the rule is in fact a specialized application of the provisions of Rule 104(b) on conditional relevancy.

This rule does not govern the situation of a witness who testifies to a hearsay statement as such, if he has personal knowledge of the making of the statement. Rules 801 and 805 would be applicable. This rule would, however, prevent him from testifying to the subject matter of the hearsay statement, as he has no personal knowledge of it.

The reference to Rule 703 is designed to avoid any question of conflict between the present rule and the provisions of that rule allowing an expert to express opinions based on facts of which he does not have personal knowledge.