The Court of Appeals for the Federal Circuit decided two cases in which the issue was whether defendant's action in modifying a patented product constituted permissible repair or impermissible reconstruction which would constitute patent infringement.

In Sandvik Aktiebolag v. E.J. Co. the plaintiff owned a patent for a drill with a shank portion and a carbide drill tip. Plaintiff sold the patented drill and expected that the drill tip would need to be resharpened and provided instructions on how to resharpen the tip. Plaintiff considered that when the drill tip could no longer be sharpened it was at the end of its useful life. Defendant provided a service which resharpened and retipped the drill bit. When the drill bit can no longer be resharpened, it must be retipped to be used.

Plaintiff claimed that defendant's retipping service constituted an infringing reconstruction of its patented drills. Defendant argued that retipping was a lawful repair of the patented drills. The lower court held that defendant's retipping was a permissible repair and not a reconstruction of the drills. The Federal Circuit, considering the totality of the circumstances including the many steps needed to retip the drill, that there was no evidence that drill retipping was done by many customers and the evidence that showed that the plaintiff did not intend that the drill be retipped, reversed the lower court decision and held that defendant's retipping of the drill bits was an impermissible reconstruction and thus was an infringement of the patent.

In Hewlett-Packard Co. v. Repeat-O-Type, the Federal Circuit affirmed the lower court decision that the defendant's modification of an ink-jet cartridge purchased from the plaintiff to permit the ink in the cartridge to be refilled was a permissible repair. The purchase of the ink jet cartridges from plaintiff carried with it an implied license to use the ink-jet cartridge. The court stated that none of the claims of the patents at issue included in their elements the ink or prohibited the modification of the ink-jet cartridge as defendant had done.

The court considered that reconstruction involved making a new article after the article was at the end of its useful life and that in this case defendant modified new cartridges. The court noted that the cartridges are specifically designed so that the ink is depleted before the patented combination as a whole is spent, before any single component of the cartridge is spent and the useful life of the patented combination is substantially longer than the life of a single reservoir of ink. The court that plaintiff did not sell the ink-jet cartridges with any limitation as to addition of ink.

These cases show that a court will consider what a defendant has done on a case by case basis and will view the totality of the circumstances including whether the modifications occur before or after the patented product is at the end of its useful life in making a determination of whether there is permissible repair or impermissible reconstruction.