Is Daubert or Frye used for expert witness testimony admissibility in Illinois?
The state of Illinois follows the Frye test for the admissibility of expert witness testimony. Donnellan v. First Student, Inc., 891 N.E.2d 463 (Ill. App. Ct. 2008). Under the Frye test, expert witness testimony is admissible if “the methodology underlying the opinion is ‘sufficiently established to have gained general acceptance in the particular field [...]