TaxProfBlog has the story.  In Swanson-Flosystems Co. v. Commissioner, No. 27975-11 (July 18, 2013), the U.S. Tax Court has held that the Internal Revenue Service is bound by the same rules affecting taxpayers involved in disputes before the Court.

In Swanson, the taxpayer served interrogatories on the IRS in the course of discovery.  Tax Court Rule 71(c) requires that all interrogatory responses be made under oath (similar requirements are in place in most federal and state courts; see, e.g., Federal Rule of Civil Procedure 33(b)(3)).  Despite this requirement, the IRS's responses to the interrogatories in Swanson were followed only by a standard signature block.  The Court held that the IRS had failed to comply with Rule 71(c) and ordered that the IRS produce interrogatory responses under oath by the end of July.