Who owns the intellectual property an open-source project with external contributions?

Question

Say a company has created a software product all by itself and decides to open-source it. As long as the contributions to the product are done by the company, the intellectual property of the the product belongs to the company. AFAIK (but correct me if I am wrong), this implies the company is free to change the license of future versions of the product, even make it proprietary.

Now the question is that if a developper external to the company commits new functionnality to the product:

• Does the company remain automatically the sole owner of the product?
• Or does it has to be written somewhere?
• If it needs to be written and it is indeed written, then is it compatible with the open-source license?
• In the case the external developper does not become co-owner of the product, is he still the owner of the isolated code he added? If so, it would mean that the code is owned twice: once in isolation by the developper (or its company), and once as part of the product by the first company.
• Do these answers depend on the country?

Answer 1

If you commit your own copyrighted work to an open source project, you keep owning the copyright. Now adding a bug fix does likely not create copyright - if there is a line of code "i = i + 2;" and it doesn't work and you change to to "i = i + 1;" which works, then finding the bug and making that change was work, but not creative so it won't create copyright.

Otherwise, for changes that do create copyright, if the company wants to keep their sole copyright, they have three choices: 1. Make you sign an agreement that you transfer the copyright to them. 2. Don't accept your change. 3. Maintain a separate version which is completely copyrighted by them.

Code published under an open source license can have any number of separate copyright holders. Which is no problem as long as they all agree. For things not covered by the open source license (like also publishing under a propriatary license), the company would need permission of all copyright holders.