Two possible types of indirect infringement are known in the United states: induced infringement and contributory infringement.

35 USC § 271(b) provides that an act of actively inducing another to infringe a patent shall itself be treated as an act of infringement.

Induced infringement can only be alleged where there is some positive act of inducement by the person being sued to another to carry out a direct infringement of that which is claimed. [217] Such a positive act may be in instructing, directing or advising the third party as to how to carry out a direct infringement. [218] Since an amendment to the law in 1984 it has been an act of infringement to supply in or from the United States all or a substantial portion of the components of a patented invention in such manner as to actively induce the combination of such components outside the United States in a manner that would constitute infringement if carried out inside the United States. [219] That is to say one can not supply from the United States a kit of parts with instructions to assemble them to produce something which if produced in the United States would be a patent infringement. [220]

The doctrine of contributory infringement, like the doctrine of equivalents, grew up to provide patentees with some additional protection against those who unfairly took advantage of their inventions. In this case the problem to be solved was that which arises where the actual infringer is someone who it may be difficult to sue, for example an individual end user who actually infringes, for example a patent for a do-it-yourself decorating technique but where it is not possible to obtain a patent for the actual article that is sold commercially. However, the application of the doctrine is not confined to method claims. It dates back to at least the 1871 case of Wallace v. Holmes [221] where the court upheld a claim for patent infringement of a claim to an oil lamp where the real invention was the burner but the claims also recited other common features of such lamps where the infringement was by sale of the burner alone. The court concluded that purchasers of the burner would complete the rest of the lamp with conventional parts themselves. Suit against the producer of the burners was preferable to a multitude of innocent purchasers of the burner who were technically responsible for completing the infringement. Again, like the doctrine of equivalents, the doctrine of contributory infringement is open to abuse. In this case the risk is that it will facilitate the ability of patentees to monopolize unpatented materials. In the hey-days of antitrust enforcement, this was a real concern and in the 1940's. The Supreme Court in the Mercoid cases [222] it was held that any attempt to control the market for unpatented goods was a patent misuse.

The 1952 Act adopted a compromise position. Under 35 USC § 271(c), contributory infringement arises when there is a sale, offer for sale or importation into the United States of a component of a patented article or a material or apparatus for use in a patented process if the component material or apparatus constitutes a material part of the invention and the person supplying it knows that it is especially made for or especially adapted for use in an infringement of a patent. The latter provision is, however, subject to a proviso that it does not apply if the article sold is a staple article or commodity of commerce which is suitable for a substantial non-infringing use. [223] In order for there to be contributory infringement, there must be a sale of a material component of the patented invention which is not itself a staple article of commerce with knowledge that the component is especially made for use in an infringement of a patented invention. There is no contributory infringement if the article sold is not especially adapted for infringement nor if the seller had no knowledge that it was so adapted. It is, however, not necessary to sue a direct infringer as well as a contributory infringer in order to succeed. [224] As noted by the Supreme Court in Dawson Chemical Co. v. Rohm & Haas Co. [225]the section provides the patentee with a "lawful adjunct of his patent rights, a limited power to exclude others from competition in nonstaple goods."

The law was changed in 1984 so as to reverse a previous decision relating to infringements by sales of kits of parts for assembly abroad. The law now provides that supply in or from the United States of a component of a patented invention that is especially made for or adapted for use in an invention and is not a staple article of commerce suitable for a substantial non-infringing use knowing that the component is so adapted or made is an infringement of a patent covering the assembled product containing the component in question even if the assembly is carried out abroad if the combination of such components within the United States would constitute a patent infringement. [226]