We don't have to speculate about whether the GPL would stand a court challenge as it has been tested in court many times in multiple jurisdictions.[1] As an as

We don't have to speculate about whether the GPL would stand a court challenge as it has been tested in court many times in multiple jurisdictions.[1] As an aside, the reason I don't think your statement would work is you don't have the ability to unilaterally bind other people by a statement you make without their agreement (ie you saying something is not a contract, because that is by definition an agreement between parties). For that reason I'm pretty sure your "all who modify my work must ..." subclause would have no legal force. The mechanism that copyleft licenses use is to grant rights to the user provided that the user adheres to the terms. That's something you can do, because it's up to you to grant whatever rights you want to grant and it's in your gift to set conditions on those grants. If users don't accept the terms of the license, they don't get granted the rights and therefore they are prevented from using or distributing the software by normal copyright law. [1] eg check out http://gpl-violations.org/news/ http://gpl-violations.org/news/ or https://sfconservancy.org/news/2019/apr/02/vmware-no-appeal/ https://sfconservancy.org/news/2019/apr/02/vmware-no-appeal/ etc