Cameron Cormack (plaintiff) brought a patent infringement suit against the United States Postal Service (USPS) (defendant). The USPS had purchased several Flats Sequencing Systems (FSS), which were mail-sorting devices, from Northrop Grumman Systems Corporation (defendant). Cormack alleged that the FSS infringed on his patent. The court granted Northrop’s motion to intervene as a defendant. Cormack filed a motion to compel documents relating to the development of Northrop’s non-FSS mail-sorting products. Cormack argued that to the extent the non-FSS products also infringed on his patent, he should be entitled to amend his complaint. Cormack also sought, for purposes of measuring damages, Northrop’s revenues and profits with respect to such non-FSS devices. Northrop opposed the motion to compel.