President Donald Trump is suing the Internal Revenue Service and the Treasury Department, and is seeking $10 billion in damages.
Trump, Donald Trump Jr., Eric Trump, and the Trump Organization sued the IRS and the U.S. Treasury Department in federal court in Miami on Thursday, following the leak of their tax returns by a former IRS employee in 2019 and 2020.
28 cfr 50.15
(10) If conflicts exist between the legal and factual positions of various employees in the same case which make it inappropriate for a single attorney to represent them all, the employees may be separated into as many compatible groups as is necessary to resolve the conflict problem and each group may be provided with separate representation. Circumstances may make it advisable that private representation be provided to all conflicting groups and that direct Justice Department representation be withheld so as not to prejudice particular defendants. In such situations, the procedures of § 50.16 will apply.
The oig not the commissioner would act on behalf of the IRS because the commissioner is a conflicted party.