Welte說，這個案例很清楚，D-Link德國公司在他們的D-GSM600 NAS產品中使用了Linux內核和其他GPL授權的代碼，但是他們沒有附帶相關的授權協議說明，或者說如何獲得相關代碼。在過去的兩年多的時間中，這種違反GPL協議的事情不下100件。
而且這也不是D-Link公司的初犯，以前他們公司也有此類事件發生，他們當時同意簽署一份聲明，表明此類事件不再發生，而且願意支付由此而引起的法律費用，以及Welte先生用於法律訴訟收集證據時的花費。但是這次不同，他們拒絕賠付Welte先生用於法律訴訟收集證據時的花費，而且聲稱，GPL協議不能夠限制他們，這顯然不可以接受，Welte先生認為，我們最終決定起訴D-Link公司。
但是可惜的是，目前好像只有在德國，有關GPL協議授權的判訴有利於GPL自由社區，GPL自由社區可以使用版權法保護置於copyleft授權下的自由軟件。
In a landmark victory for the GPL license, a civil court in Germany has ruled against D-Link Germany GmbH for violating the terms of the most popular free software license. The lawsuit was filed by Harald Welte, a respected Linux hacker who tracks and eliminates illegal use of software protected by the GPL through his gpl-violations.org project. In a brief email exchange, Welte explains the nature of the violation and how he went about collecting evidence.
"It was a very straight-forward case," says Welte, describing how D-Link used the Linux kernel and other (L)GPL licensed software in their D-GSM600 NAS product without including a copy of the license text, the full corresponding source code or a written offer on how to obtain it. In the last 2.5 years, Welte has discovered over 100 instances of such violations.
This wasn't the first D-Link GPL violation. "Previously, D-Link signed a declaration to cease and desist and paid my expenses for legal fees, test purchase and reverse engineering," explains Welte. This time, however, D-Link refused to reimburse his expenses and sent a letter indicating that they didn't think the GPL was legally binding on them. "This is obviously not acceptable," says Welte, who runs the project out of his own pocket.
"Furthermore, even in those previous cases, D-Link had a lot of problems and caused delays when it came to providing the "full corresponding source code" as mandated by the GPL," Welte notes.
So gpl-violations.org filed a civil case with the district court of Frankfurt, Germany in March 2006 seeking a judgment supporting his copyright claims based on the GPL. In addition, Welte wanted the court to order D-Link to reimburse gpl-violations.org for the expenses of the out-of-court enforcement.
That is when the real work began. "The way German civil cases work, is that anything that is not denied is assumed to be true. D-Link made it hard for us by denying everything. They denied that the source code they published would match the object code running in the device," explains Welte.
They also questioned the nationality of the two authors of the piece of code under dispute. "We basically had to provide evidence to the court that all things they deny are in fact true, including that the authors, Werner Almesberger is an Austrian Citizen and David Woodhouse is a UK citizen," shares Welte.
Most of his time was spent in preparing evidence on the actual copyright infringement, which Welte shares, meant "looking at the original releases of msdosfs, initrd and mtd, the three parts of the Linux kernel, based on which I sued, from about a decade ago, and comparing the source code of those original versions with the actual source code present in the D-Link D-GSM600. Then highlighting line by line, function by function, which piece of what code can be found where, coloring blocks of code, etc. Apart from that we also had to read backlogs of the respective development lists, to find proof for details on the development process back then. Finally, both Werner Almesberger and David Woodhouse had to be asked about further details, like which pieces of code they wrote when, who contributed at which time and what part, and such details."
But Welte is quick to add that it is impossible to take up any such case without having legal assistance from a lawyer who knows the issues, how the software development process works, what source code looks like, etc. He found such a parter in Dr. Till Jaeger, co-founder of the Institute for Legal Issues of Free and Open Source Software. Welte adds that Dr Jaeger has also co-authored some books on the legal issues of FOSS, such as "Die GPL kommentiert und erklaert" which is published by O'Reilly Germany. "The title can be translated as 'The GPL, annotated and explained'," explains Welte, adding "he was also involved in translating the Creative Commons licenses in to the German language, as well as the German legal system."
Thanks to the developer's research and the lawyer's understanding, on September 6th, 2006, the court in its judgment, backed the claims made by gpl-violations.org and acknowledging the violation of the GPL by D-Link ordered it to reimburse gpl-violations.org for legal expenses plus the costs of purchasing and re-engineering the product.
More importantly the court upheld the validity of the GPL in its ruling, currently available only in German, affirming that copylefted software can be defended using copyright laws.