Is patent infringement transitive?

Question

I'm curious about a the following scenario, and I haven't been able to find a clear answer so far.

Say a piece of software X uses another piece of software Y, for example Y might be an open source library.

If Y is then found to be infringing a patent held by a third party, is X also infringing and therefore potentially subject to litigation?

Does the question generalize to X being any use of Y, not just new software?

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Update - I (and other readers) should appreciate that the answers to this question should not be taken as legal advice.

Answer 1

I think also X is infringing the license.

It's a duty of the developer of X to be sure that what he is using is effectively licensed as open source. Since he is forced to accept whatever license is on Y he will implicitly go with whatever license is used for the not free part of Y.

Answer 2

X is certainly guilty of using and/or selling patented property, which (in this case) constitutes contributory infringement.

Your good faith on product Y and ignorance of Y's direct infringement may be a sufficient defense against a lawsuit.

Patent statute, at 35 U. S. S 271(c):

Whoever imports into the United States a component of a patented machine, manufacture, combination or composition, or a material or apparatus for use in practicing a patented process, constituting a material part of the invention, knowing the same to be especially made or especially adapted for in an infringement of such patent, and not a staple article or commodity of commerce suitable for substantial noninfringng use, shall be liable as a contributory infringer.

But hey, I'm an engineer, so cum grano salis... you need to ask a lawyer in your jurisdiction.

The bottom line is that if you are using a resource that violates a patent, stop using it.

Answer 3

This depends on the implementation of 'use'.

If Y is a library or another executable that is not incorporated into X, then X is not in violation. You can make external calls and expect something else to be there. If X is distributed with Y (in an installer package or some such), then you indeed have contributory infringement.

If the code is linked directly into the code or copy-pasted and compiled into the image, then X could be guilty if Y is.

This is a fairly nuanced issue. The outcome will probably depend on exactly what was used and how.

Answer 4

Here are a couple examples of patent infringement transitivity.

The first example is an article that provides a summary of Microsoft Corp. vs Timeline Inc. Microsoft settled with Timeline for patent infringement in SQL Server 7.0. However Timeline had an issue with users who modified (via add-ons, I guess) the patented parts of the software, and claimed that those users were infringing, as well. Microsoft won the initial trial defending its users, but Timeline appealed and won.

There's also a well-known and controversial deal between Microsoft and Novell. Novell paid Microsoft who in return would not sue SUSE Linux users for patent infringement. The controversy is far reaching, but in its simplest form it can be used to show that Novell was concerned that if it infringed on patents, its users were potentially liable.

Microsoft (and other companies) offer indemnity for the users of its software against all IP lawsuits related to licensing of the software. This article mentions other suits such as one Sun Microsystems settled with Kodak concerning Java and its users. Microsoft's goal is to make users think twice about using open source that offers no such guarantee.