Bukkit's legal status in question after Mojang takes ownership

You may recall that Mojang, the creators of Minecraft, recently took full ownership of the CraftBukkit server software after it's primary developer tried to shut it down. Well now there is some internal legal trouble within the Bukkit project, and all the Bukkit downloads have been removed because of it.

To understand what has happened, it's important to know the difference between CraftBukkit and Bukkit. Bukkit, also called the Bukkit API, is the code that server plugins are designed to use (and link it with the server). CraftBukkit is the actual server software you download and use, that uses the Bukkit API to power it's plugins.

The next part is a bit tricky, and I may have interpreted it incorrectly (I am by no means a legal expert). A developer for the Bukkit API emailed Mojang reporting that CraftBukkit infringed on the copyright license of Bukkit. The license that Bukkit uses, known as the GNU General Public License Version 3, requires any project that uses it must be free, have the code available, and link to the original project (aka Bukkit).

From what I can tell, it seems like CraftBukkit has stopped giving credit to Bukkit for their work (therefore violating the GPL v3 license). Mojang responded with the following statement:

Mojang has not authorized the inclusion of any of its proprietary Minecraft software (including its Minecraft Server software) within the Bukkit project to be included in or made subject to any GPL or LGPL license, or indeed any other open source license

As the Minecraft Server software is included in CraftBukkit, and the original code has not been provided or its use authorized, this is a violation of my copyright. I have a good faith belief the distribution of CraftBukkit includes content of which the distribution is not authorized by the copyright owner, it's agent, or the law.

You are more than welcome to intepret the legal letter for yourself at the source link below, but either way all Bukkit downloads have been removed from the site. We will have to wait for Mojang and Bukkit/CraftBukkit to sort all this out, and maybe in the meantime my head will stop spinning.

UPDATE: Reddit user the_snatch has summed up the issues at hand much better than I have, so here's what he had to say:

With all of the confusion going on regarding the Bukkit project, I've noticed that only a few people here have any sort of understanding regarding licensing and copyright. I'm no expert myself, though. I am a software engineer, but I also have a limited understanding. The point of this thread is that I'd like to share what I understand to be true and possibly be corrected in the hopes that we can all leave a little more enlightened. Please, do correct me if I'm wrong.

• Minecraft: A trademarked name of a game released under a proprietary license.
  
  
  
  • It is illegal for anyone other than the owner to use the name Minecraft without permission.
  
  
  • It is illegal for anyone other than the owner to distribute the software without permission.
  
  
  • Reverse engineering it in the United States is legal as long as the software was obtained legally and that it wasn't done to circumvent access controls put in place by the software.
  
  
  
  

Mojang is not required by law to alter their license. The license(s) of derivative works of Minecraft do not apply to it. The source code was obtained by the Bukkit team in a legal manner. The Bukkit team's distribution of the Minecraft server software was illegal, but that changed once Mojang acquired Bukkit.

• Bukkit: A trademarked name of a development API released under the GPL.
  
  
  
  • It is illegal for any one other than the owner to use the name Bukkit without permission.
  
  
  • It is legal for anyone to modify and distribute as long as the current GPL, or a later version, remains in place.
  
  
  • Source code must be freely available when distributed.
  
  
  
  

People confuse Bukkit with CraftBukkit a lot. Bukkit is the API developers use to create plugins. Mojang owns the the name Bukkit and the project Bukkit.

• CraftBukkit: A trademarked name of a modification to proprietary software, released under LGPL.
  
  
  
  • It is illegal for any one other than the owner to use the name CraftBukkit without permission.
  
  
  • It is legal for anyone to modify and/or distribute, but releasing the source code is not required unless it is modified.
  
  
  
  

CraftBukkit is a derivative work. Parent projects are not bound by child licenses. Mojang is not required to open the source to Minecraft just because a derivative projects has been released under the GPL. Mojang owns the name CraftBukkit and the CraftBukkit project.

With all this in mind, we can say Mojang is not breaking any laws by continuing the Bukkit and CraftBukkit projects.

Now, on to the complaint by Wolfe:

The provided license requires the use of included or linking code to provide the original source under the GNU GPL license version 3, or any later version.

• This is false. We know that CraftBukkit is a derivative project and that the parent project does not fall under the requirements of the child project.

Mojang has not authorized the inclusion of any of its proprietary Minecraft software

• This is false. Mojang, since its acquisition of Bukkit and CraftBukkit, has allowed the inclusion of it's proprietary software.

UPDATE 2: Jens has replied to the above Reddit post, saying "I know it's probably a mistake to comment here, but I just wanted to point out that Bukkit (the API) is GPL and CraftBukkit (the implementation of Bukkit) is LGPL. In other words the other way around. Doesn't change your conclusions, though."

Source: Bukkit