I have an invention that combines 2 pieces of what would be useless components if separated. Hence the 2 pieces cannot be patented as separate inventions.

Let's suppose that 1 of those 2 pieces needs to be manufactured and the other piece is a common household item.

Is it possible for a company to manufacture the piece that requires manufacturing and sell it to buyers who will assemble the final invention by combining the house hold item piece with the piece that they bought from this company?

Is this infringement?

If it is infringement, who is the transgressor? The company or their customer?

  • Do you know for a fact that the manufactured item is patented? If so the answer depends on the specifics of the patents.
    – Eric S
    Commented Apr 5, 2022 at 17:42
  • 1
    If the new thing (A) can be readily combined with an existing item (B) to create something useful then the new thing has a use - to be combined with the existing thing. The law requires claims to be for useful things but that is a very very low bar in practice as long as your claim is not susceptible to be categorized as "abstract". You will get a better answer if you tell us more about the question. For example what are your goals? Would patenting item A be helpful? Or is there already an A+B that is patented are you are trying to get around the patent by only selling B?
    – George White
    Commented Apr 5, 2022 at 21:45
  • My goal is to patent A+B. But the problem is, then other companies can sell A and B separately, which the consumer can buy and assemble into A+B. Commented Apr 5, 2022 at 21:49

2 Answers 2


If you patent the combination of the two items and others sell a a part with no general use other than to be combined with something else then they are probably indirect infringement. Especially if they include directions for doing so or otherwise promote that use.

Technically it would be the end user who was a direct infringer but you do not need to go after them to go after the indirect infringers.

If a key portion is novel and not hard to combine with the more standard remaining portions then this patent for a retractable suitcase handle might be a good model for you.

If the patentee had included the suitcase in the claim then someone could make the handle without direct infringement.


If the manufacturer of one or both components markets either or both of these components as able to be assembled to comprise the patented innovation, the patent holder can sue that manufacturer for inducement of patent infringement, because the manufacturer is directly informing the buyer to purchase the component(s) to then assemble the separate components to have the buyer infringe the patent. Even if the manufacturer does not actively advertise such combination to achieve the patented innovation, merely pointing out in, say, engineering-design manuals is enough of a threshold to cross to prove inducement. Sometimes even lower thresholds might apply in wink-&-a-nod-esque situations, as long as the implication to infringe the patent is in the gist of various communications taken as a whole over time.

Please study Power Integrations, Inc. v. Fairchild Semiconductor Int’l, Inc. in the USA's Federal Circuit for one of the most-recent precedents on the finer points of inducing a 3rd party to infringe a patent. Obviously, that case refers to multiple prior precedents that it itself studies within the ruling.

In addition to the linked case ruling itself, please perform a Bing or Google search for “Power Integrations, Inc. v. Fairchild Semiconductor” as you will find numerous filings from the plaintiff & defendant as well as numerous legal-forum & legal-firm discussions of this case.

  • If you could provide a link to the cited case it would improve the otherwise helpful answer.
    – Eric S
    Commented Apr 7, 2022 at 15:41
  • @EricS, done. Thank you for your valuable suggestion. Commented Apr 7, 2022 at 19:33

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