As a follow up to [Does a BSD-licensed project need a signed statement from each contributor?](https://softwareengineering.stackexchange.com/q/185566/61231):

There are several reasons why an open source project might want to get copyright assignments from its contributors. For example:

* To allow the project author to sue for infringement (as only the copyright holder can do so). This is also why FSF requires such an assignment.
* To prevent future problems with the contributors, such as they claiming later that they didn't release their contribution under the same OS license.

Another reason is if a company releases its software under (L)GPL and also sells it under a commercial license. Then a copyright assignment is necessary so that the company can include contributions under the commercial license. If the contributors are informed beforehand, this is fair.

But if the company has the copyright to everything, it can do basically anything with the sources, something that the contributors wouldn't agree on. It can switch to another license, like from (L)GPL to a non-copyleft license, or even stop releasing the project as open-source and switch to proprietary licensing only. This has [reportedly happened with SourceForge](https://softwareengineering.stackexchange.com/a/102794/61231).

So what is a fair way to handle the problem? If the project owner doesn't get copyright assignments, (s)he can get into problems in the future. If (s)he does, the work of the contributors can lose its license or open-source status. Is there a solution to this dilemma that is fair to both sides?

As I'm not a native speaker, I might used wrong legal terms. Please feel free to correct the question.

Related:

* [How to get contributors assign copyright for copyright holder?](https://softwareengineering.stackexchange.com/q/136671/61231).
* [Copyright assignment on open source projects](https://softwareengineering.stackexchange.com/q/102693/61231)