Expresses the sense of the Congress that: (1) expert testimony concerning the nature and effect of domestic violence, including descriptions of the experiences of battered women, should be admissible when offered in a State court by a defendant in a criminal case to assist the trier of fact in understanding the behavior, beliefs, or perceptions of such defendant in a domestic relationship in which abuse has occurred; (2) a witness should be qualified to testify as an expert witness, with respect to a case in which abuse has occurred, based upon the witness's knowledge, skill, experience, training, or education, and should be permitted to testify in the form of an opinion or otherwise; and (3) domestic relationships about which such expert testimony should be admissible include relationships between spouses, former spouses, cohabitants, former cohabitants, partners or former partners, and between persons who are in, or have been in, a dating, courtship, or intimate relationship.