On May 6, 2024, Kostelanetz attorneys Brian Wille and Usman Mohammad filed an amicus brief with the United States Court of Appeals for the D.C. Circuit in a tax whistleblower case captioned In re Sealed Case, D.C. Circuit Case No. 24-1001. Kostelanetz filed the amicus brief on behalf of another whistleblower in a pending Tax Court case, arguing that de novo review should apply in actions brought under the tax whistleblower statute, 26 U.S.C. § 7623(b). In 2018, the Tax Court held in Kasper v. Commissioner, 150 T.C. 8 (2018), that a deferential “abuse of discretion” standard of review would apply in cases challenging award decisions issued by the IRS Whistleblower Office (“WBO”). The amicus brief filed by Kostelanetz argues that Kasper’s holding ignored the plain language of Section 7623(b), which provides that the WBO “shall” make a whistleblower award where the statutory preconditions for recovery have been satisfied, as well as the underlying purpose of the whistleblower statute, a central goal of which is to provide oversight and review of the IRS’s actions in ruling on whether a whistleblower award was due and owing. In its amicus brief, Kostelanetz argues that these factors and others require that de novo (rather than abuse of discretion) review apply in cases challenging award decisions by the WBO.