Jones Day filed an amicus brief in the Illinois Supreme Court on behalf of the Taxpayers' Federation of Illinois regarding the standard of review for Illinois Tax Tribunal decisions.

On behalf of the Taxpayers' Federation of Illinois ("TFI"), Jones Day submitted a friend of the court brief to the Illinois Supreme Court in Horsehead Corporation v. Illinois Department of Revenue, Case No. 124155 (Ill. Sup. Ct.). TFI urges the court to eschew deference to the Illinois Independent Tax Tribunal on its statutory interpretations, in this case made to deny a taxpayer's claim to a statutory exemption from use tax on certain materials used in its manufacturing process. The Illinois Appellate Court upheld the Tribunal's decision, introducing the novel theory that the statutorily required tax expertise of the Tax Tribunal judges bound the appellate court to apply a deferential "clearly erroneous" standard of review to the Tax Tribunal's statutory interpretations, as opposed to deferring only to its factual determinations.

TFI argues that the standard of review for legal determinations of the Tax Tribunal should be de novo, the same as it would for a judicial trial court, once full account is taken of the constitutional roles of the courts and of executive agencies, and of the intent of the General Assembly when creating the Tax Tribunal. Briefing was completed on August 8, 2019. The court will hear oral arguments in its fall session. The Taxpayers' Federation of Illinois amicus curiae brief can be accessed here.