Is technology in expired patents open source?

Question

After a patent expires people are free to use it.

Does this means, that the technology described in the claims are then Open Source?

Answer 1

We have to differentiate here. A patent describes a technology on a general level. And patents can be implemented, by hardware or software. The owner of a patent can restrict implementations as he sees fit. The implementor has independent of the patent a normal copyright on his work. This is a problem for open source, as the open source licenses usually only covers copyright (well-known exceptions are GPL 3 and Apache 2, that address patent issues), a patent still can restrict the rights and make it in practice not open source. An example is the original bzip-implementation that was replaced with bzip2 to avoid conflict with a patent from IBM.

The patent-owner can also give a patent-license, that allows similar rights to open source. This is done from some companies in patent pools, the Open Invention Network is an example for this.

Now, what happens if the patent expires? That means the technology covered can now freely be implemented. Existing implementations are still covered by their copyright. But the expiring of the patent might open the door to an open source implementation.

TL;DR: The patent itself and existing implementations don't become open source, but it allows for open source implementations.

Answer 2

No. These are public domain, which can be interprated as kind of Open Source, but in fact it's just public knowledge as the wheel is.