A person's handwriting may be authenticated by a lay witness -- i.e., a lay witness may identify the author of handwriting -- if the witness is personally familiar with the putative author's handwriting and the witness did not acquire such familiarity for purposes of the litigation.

Tavares v. Michigan Fishing, Inc., 937 F. Supp. 84, 86 (D. Mass. 1996) (holding, in plaintiff injured fisherman's action against defendant vessel owner for damages due to vessel's unseaworthiness, that plaintiff counsel's....Evidence of the existence or non-existence of liability insurance is not admissible on the issue of negligence or wrongful conduct.

Fed. R. Evid. 103(a) ("(a) Effect of erroneous ruling. Error may not be predicated upon a ruling which...excludes evidence unless a substantial right of the party is affected, and (1) Objection. - In case the ruling is one admitting evidence, a timely objection or motion to strike appears of record, stating the specific ground of...If a trial court overrules an objection to evidence, an appellate court will review the trial court's ruling only if the opponent made a specific objection at trial; if the opponent of the evidence made a general objection and the trial court overruled the objection, it will be said that the opponent waived or forfeited its claim of error by making a general objection.

See United States v. Leichtman, 742 F.2d 598, 603-604 (11th Cir. 1984) (upholding trial court's admission into evidence of a marijuana transaction where it was inextricably intertwined with the evidence necessary to prove the crime charged as it was necessary to prove motive, to establish context,...Other crimes, wrongs, or acts are admissible and do not violate the prohibition against the use of character to show conduct if such acts are admissible to show the context of an event at issue at trial or to tell the full story or an intelligible story of a series of events at issue at trial.