Enforcing GPL without copyright
<p>From what I understand the GPL license can only be enforced by the copyright holder.</p>

<p>Therefore, given a scenario like this:</p>

<p>A developer finds an abandoned software project licensed under GPL.</p>

<p>S/he builds upon the project and extends the functionality (which I'm assuming would counts as derivative work).</p>

<p>S/he releases the improved source code to everyone else.</p>

<p>At some point the GPL license has been violated.</p>

<p>Could the new developer enforce the license if the original copyright holder is long-gone or undisclosed in the original work?</p>

<p>Or is the license only enforceable by the original creator? </p>

<p>There are now 2 works. An original, abandoned work, and a new, derivative work. The original creator owns the copyright over the original, and the new person owns copyright over the derivative he created.</p>

<p>In your scenario, it will be the new creator, who will have the right to sue, if the gpl of the new work has been infringed</p>

software open-source-software gpl