Let's say there is a software company. This company is developing a Digital Signal Processing software library. The library doesn't constitute an application itself but it is meant to be sold to be used in a bigger software. For simplicity, we assume that the library has been written from scratch, without the use of any other external libraries.

Anyway the library implements some algorithms that have been patented, from other entities, for specific applications.

Does the company has to care about patents at all? Does the company has to warn the client about the specific patented applications? Since the library has been written from scratch, may the client pretend to use the library to implement a patented application?

  • Spalla - for clarity, when you say that some algorithms have been patented, are those ones patented by other entities? Commented Feb 22, 2014 at 17:54
  • Yes, I mean patented from other entities. I edit the question
    – Spalla
    Commented Feb 22, 2014 at 22:14

2 Answers 2


"Written from scratch" gets around copyrights but not around patents. In very general terms patents protect the functionality of something while copyrights protect a specific expression that might or might not be functional.

What you deliver might infringe a claim in a patent. Or what you deliver might intent a claim whenever it is executed. Or what you deliver might infringe a claim when used with certain data or certain other bits of software. In this last case you might be ok because your part has many other non-infrging uses, or you might be in trouble because you market your product specifically for an infringing use. The wording of a claim in question is key. You might infringe directly or might contribute to you customer's infringement. Or you might induce your customer's infringement. Or you might be fine.

  • Are you saying that one of the key points to avoid patent troubles (just for the company) will be the way the company is making advertisement?
    – Spalla
    Commented Feb 22, 2014 at 22:23
  • Even if your product itself doesn't infringe and has many non-infringing uses you can still get in trouble if you encourage and facilitate an infringing use.
    – George White
    Commented Feb 22, 2014 at 22:40

The answer is if any function your program causes any computer to perform infringes on anyone's patent, then you're wide open to a lawsuit from the patent holder. It doesn't matter that the code is original since it's the functionalty,(in reality an idea), that is patented. So if your code causes the patented functionality to be performed, stop thinking- you've infringed, case closed. There is no escaping exposure to liabilty.

The fact that software patents are in reality patents on ideas, and common ideas at that is the reason developers are so against them.

You always have the option of not selling software where software patents are permitted. Other than doing that, there is no way out.

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