What is the legal test for a document that is both a tax return and a grand jury subpoena?

For such dual purpose documents, courts examining this issue seem to draw a line at whether it can be said that there is an "independent purpose . . . truly separable from the anticipation of litigation." In re Grand Jury Subpoena, 357 F.3d at 909. In In re Grand Jury Subpoena, the court contrasted two cases to illustrate the dichotomy: In re Special September 1978 Grand Jury, 640 F.3d 49 (7th Cir. 1980) with United States v. Frederick, 182 F.3d, 496 (7th Cir. 1999). The court distinguished the two cases, explaining the protection found applicable in In re Special September 1978 Grand Jury but not in Frederick, because the accountant's worksheets at issue in Frederick were part of a tax return preparation and that was a "separable purpose from litigation preparation."

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