Is scientific or expert evidence admissible only if the expert evidence is generally acceptable to scientists or experts or must the trial court make an independent determination of the validity and reliability of such evidence?

United States v. Safavian, 435 F. Supp. 2d 36, 43-44 (D.D.C. 2006) (holding that "context and content" established that defendant adopted some of other people's e-mail messages by forwarding them).An adoptive admission is exempt from the prohibition against hearsay evidence.

United States v. Jackson, 335 F.3d 170, 178 (2d Cir. 2003) (upholding trial court's exclusion of co-conspirator's plea allocution under Rule 804(b)(1) because (1) "[co-conspirator] was unavailable at Jackson's trial....If the declarant is unavailable, Federal Rule of Evidence 804(b)(1) or a comparable State rule creates a hearsay exception for testimony given as a witness at another hearing of the same or a different proceeding, or in a deposition taken in compliance with law in the course of the same or another proceeding, if the party against whom the testimony is now offered, or, in a civil action or proceeding, a predecessor in interest, had an opportunity and similar motive to develop the testimony by direct, cross, or redirect examination.

Fed. R. Evid. 901(b)(4) ("Appearance, contents, substance, internal patterns, or other distinctive characteristics, taken in conjunction with circumstances.").Federal Rule of Evidence 901(b)(4) and comparable State rules allow a thing or matter to be authenticated by its distinctive characteristics considered in conjunction with circumstances.