Illinois Statutes Chapter 725. Criminal Procedure § 5/115-7.4. Evidence in domestic violence cases

(a) In a criminal prosecution in which the defendant is accused of an offense of domestic violence as defined in paragraphs (1) and (3) of Section 103 of the Illinois Domestic Violence Act of 1986, or first degree murder or second degree murder when the commission of the offense involves domestic violence, evidence of the defendant's commission of another offense or offenses of domestic violence is admissible, and may be considered for its bearing on any matter to which it is relevant.

(b) In weighing the probative value of the evidence against undue prejudice to the defendant, the court may consider:

(c) In a criminal case in which the prosecution intends to offer evidence under this Section, it must disclose the evidence, including statements of witnesses or a summary of the substance of any testimony, at a reasonable time in advance of trial, or during trial if the court excuses pretrial notice on good cause shown.

(d) In a criminal case in which evidence is offered under this Section, proof may be made by specific instances of conduct, testimony as to reputation, or testimony in the form of an expert opinion, except that the prosecution may offer reputation testimony only after the opposing party has offered that testimony.