Recently, I decided to research a method of consolidating an expertise and researched any pre-existing tools which might already encapsulate my process or aid (be it software or hardware).

I came across a pre-existing hardware device, able to convey the process I was envisaging, it is available for purchase but at a not inconsequential price, possibly hindering access to its definite utility.

If the first line(s) of patents, for currently sold, physical hardware, begins with a phrase explicitly including "...a device to...", would my programming of a purely software-based [mobile] emulation app, containing an interface analogous, but not identical, to the real world device, infringe on that, original, hardware device?

  • When you say “first line” do you mean of a claim?
    – Eric S
    Commented Feb 26, 2022 at 13:52
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    What is relevant is not the first line of the whole document but of each of the claims. They are relatively short numbered sections at the end of the document and are introduced with the word “claim”. The patent as a whole might be about a device yet have one or more method claims that a pure software product could infringe.
    – George White
    Commented Feb 26, 2022 at 16:01
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    The word device does mean something relevant if it is the preamble to a claim.
    – George White
    Commented Feb 26, 2022 at 17:07
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    Then the only advice I can provide is to consult with an actual patent attorney. In the meantime, just focus on the claims. If you are unsure what a claim means you could post a question about it where you edit out the technical bits to anonymize things.
    – Eric S
    Commented Feb 27, 2022 at 12:35
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    @BigRich That is fine. Claims are legal writing so parsing them can be hard for inventors. Remember, to infringe on a claim you have to implement every element in the claim. If there are 5 elements and you only do 4 of them you don’t infringe.
    – Eric S
    Commented Feb 28, 2022 at 14:40

1 Answer 1


There are only a few statutory categories that any claim in a U.S. patent must fall into - "process, machine, manufacture, or composition of matter". An apparatus, device or system would be a machine or possibly a manufacture (meaning something that was manufactured). A method would be a process. Methods are defined in terms of steps, while machines etc. are defined in terms of structure or in terms of functions inherent do to the structure.

A program would not directly infringe a claim that starts "A device . . . ". But the same patent may have method claims. To make this more complicated, a system (a machine) can be defined in terms of what it does when you turn it on (a process) so wording in the claim include steps but the claim is not to a method but a machine that carries out the steps. Your initial thought to look at the preamble is key to this.

If your software works by being installed on a phone then your software is not a "device" but the phone + software is a device. You are not directly infringing a device claim or system claim in that case if you just provide the software.

But there are also a few forms of indirect infringement that you may be guilty of practicing even if you do not make or sell an actual claimed device. This includes induced infringement and contributory infringement.

  • I will look more carefully into what induced infringement and contributory infringement are, I thank you.
    – Big Rich
    Commented Mar 3, 2022 at 12:45

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