Evidence

Only to matters of which the witness has personal knowledge — facts the witness personally perceived. Evidence must be introduced sufficient to support a finding of personal knowledge.

A witness may review any writing to refresh present recollection; the writing itself is not evidence. The adverse party may inspect it, cross-examine on it, and introduce relevant portions.

Refreshing recollection (612) uses a writing only to jog memory and the witness then testifies from memory; recorded recollection (803(5)) applies when memory cannot be revived and the record is read into evidence.

By a timely objection or motion to strike stating the specific ground, unless the ground is apparent from context.

By an offer of proof showing the substance of the excluded evidence, unless the substance is apparent from context.

When it is (1) rationally based on the witness's perception, (2) helpful to understanding testimony or determining a fact, and (3) not based on scientific, technical, or specialized knowledge.