Rare is the case [excepting expert testimony] where a witness is not describing what s/he claims to have seen, heard, smelled, touched or tasted. Without that sensory connection to the item at issue, there would be no relevance; and most lawyers abstain from calling a witness to testify to what was behind a closed door or occurring in a far-away location. So what’s the “personal knowledge” fuss? Perhaps the answer comes, first, from acknowledging that for some reason the drafters of the Federal Rules [and corresponding state codes of evidence] felt the need to include it in addition to the foundational requirement that only relevant evidence be admitted. Indeed, the comment to the personal knowledge rule – Rule 602 – makes clear that it is merely “a specialized application of the provisions of Rule 104(b) on conditional relevancy.” Yet the Rule is there – so it must have some meaning. For the advocate, the reason for the ‘fuss’ derives directly from the existence of the rule – it is now a tool available to a …