(

a) In a criminal action, expert testimony is admissible by either the prosecution or the defense regarding intimate partner battering and its effects, including the nature and effect of physical, emotional, or mental abuse on the beliefs, perceptions, or behavior of victims of domestic violence, except when offered against a criminal defendant to prove the occurrence of the act or acts of abuse which form the basis of the criminal charge. (

b) The foundation shall be sufficient for admission of this expert testimony if the proponent of the evidence establishes its relevancy and the proper qualifications of the expert witness. Expert opinion testimony on intimate partner battering and its effects shall not be considered a new scientific technique whose reliability is unproven. (

c) For purposes of this section, “abuse” is defined in

Section of the Family Code, and “domestic violence” is defined in

Section of the Family Code and may include acts defined in

Section 242, subdivision (

e) of

Section 243,

Section 261, 273.5, 273.6, 422, or 653m of, or former

Section of, the Penal Code. (

d) This

section is intended as a rule of evidence only and no substantive change affecting the Penal Code is intended. (

e) This

section shall be known, and may be cited, as the Expert Witness Testimony on Intimate Partner Battering and Its Effects

Section of the Evidence Code. (

f) The changes in this

section that become effective on January 1, 2005, are not intended to impact any existing decisional law regarding this section, and that decisional law should apply equally to this

section as it refers to “intimate partner battering and its effects” in place of “battered women’s syndrome.”