[1] In doing so, the Court rejected the narrower control group test that had previously governed many organizational attorney–client privilege issues.

[3] In subsequent cases, failure to give an Upjohn warning has led to the employee being able to claim privilege over communications with company lawyers.

The Sixth Circuit had also ruled that the work-product doctrine did not apply to the tax summons the company had received as a result of some of its unlawful business practices.

This view was followed consistently by the federal courts until 1970, when the United States Court of Appeals for the Seventh Circuit adopted a "subject matter" test under which other employees' communications with company lawyers could be subject to privilege, if made in relation to their employment and at the direction of superiors.

[2] In a unanimous 9–0 decision, Justice William Rehnquist wrote the opinion of the Court in which it reversed the Sixth Circuit's holding.