Can I upgrade all CC 3.0 licenses to 4.0 counterparts when creating a joint dataset?

Question

I am planning on creating a dataset which contains data with different licenses. I decided to create differently-licensed versions of my dataset that contain different combinations of data from different licenses. I based the combination on this article. Hence, the following versions are planned, including elements of the licenses noted below each version:

• public-domain will contain work licensed under:
  • public-domain
• cc0-1.0 will contain work licensed under:
  • public-domain
  • cc0-1.0
• cc-by will contain work licensed under:
  • public-domain
  • cc0-1.0
  • cc-by
• cc-by-sa will contain work licensed under:
  • public-domain
  • cc0-1.0
  • cc-by
  • cc-by-sa
• cc-by-nc will contain work licensed under:
  • public-domain
  • cc0-1.0
  • cc-by
  • cc-by-nc
• cc-by-nc-sa will contain work licensed under:
  • public-domain
  • cc0-1.0
  • cc-by
  • cc-by-nc
  • cc-by-nc-sa

It seems clear to me that I can combine works released solely under 3.0 versions and works released solely under 4.0 versions. E.g., I would combine cc-by-3.0 and cc-by-nc-3.0 as cc-by-nc-3.0; or cc-by-nc-4.0 and cc-by-nc-sa-4.0 as cc-by-nc-sa-4.0.

However, can I also combine both works with 3.0 licenses and works with 4.0 licenses into a single 4.0 license? I only found information on SA licenses. Nevertheless, can I, e.g., combine a work licensed under cc-by-3.0 and a work licensed under cc-by-nc-4.0 and release it as cc-by-nc-4.0?

Answer 1

Take a closer look. A collection of facts (data) might not even be copyrightable, so the "licenses to the original collections" might very well be moot anyway.

As a general rule, you can't "change license", only the owner of the rights can (re)license any work under a different license. The GPL is explicit in this, it states e.g. "you can use this under GPLv2, or, at your option, under any later version of GPL". Check if the licenses you cite allow such changes, or combining with others. Often it is enough that the licenses don't contradict and you are allowed to use in combination, but each piece stays under the original license.

I am not a lawyer, so the above is a layman's take. It is a very complicated area.