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On March 7, 2003, the SCO Group (formerly known as Caldera Systems) filed a $1 billion lawsuit in the US against IBM for allegedly "devaluing" its version of the UNIX operating system. The amount of alleged damages was later increased to $3 billion. SCO claimed that IBM had, without authorization, contributed SCO's intellectual property to the codebase of the open source, Unix-like Linux operating system. In May 2003 SCO Group sent letters to members of the Fortune 1000 and Global 500 companies warning them of the possibility of liability if they use Linux. Because of this, the stock price of SCO (Nasdaq stock symbol SCOX) has skyrocketed.

Since then, the claims and counter-claims made by both sides have escalated, with both IBM and Linux distributor Red Hat starting legal action against SCO, and SCO making threatening noises toward Linux users who do not take out SCO UNIX licences.

On September 30, Judge Kimball granted the SCO Group's request for a delay until February 4, 2004, "to file any amended pleadings or add parties to this action". This pushes the start of the actual lawsuit back until 2005.

Table of contents
1 SCO's claims
2 Free software community reaction
3 The GPL issue
4 Novell enters the controversy
5 Fear, uncertainty and doubt
6 Allegations of reverse copying
7 IBM's AIX licence
8 Scheduler code claims
9 Increased damages claims, and read-copy-update claims
10 SCO announces that it will not sue its own customers
11 SCO to offer a "Linux licensing program"?
12 IBM points out SCO's GPL licensing of code
13 Red Hat legal action and SCO's response
14 SCO announces licensing fees
15 IBM counterclaims against SCO
16 Discovery
17 Examples of controversial code revealed
18 New IBM counterclaims
19 SCO acts against SGI
20 First discovery hearing
21 Copyright claims, December 2003
22 External links

SCO's claims

Though the lawsuit itself has been rather consistent in its claims of breach of contract and misappropriation of trade secrets, statements made by SCO in press releases and interviews have changed its claims repeatedly as the affair has progressed; SCO has also both claimed and denied that the alleged copyright violations involved the Linux kernel.

It has been reported that SCO has variously threatened to sue Linux users and even Linus Torvalds, head of the Linux programming project, himself. Computerworld reported that SCO's Chris Sontag said, regarding the alleged infringements:

"It's very extensive. It is many different sections of code ranging from five to 10 to 15 lines of code in multiple places that are of issue, up to large blocks of code that have been inappropriately copied into Linux in violation of our source-code licensing contract. That's in the kernel itself, so it is significant. It is not a line or two here or there. It was quite a surprise for us."

SCO refuses to allow access to the samples of code that contained the alleged copyright violations except under a non-disclosure agreement (NDA). SCO's NDA would not only require that the signer to keep confidential which lines of code SCO contested, but would also require that they hold confidential any information SCO told him, even if they already knew that information before being informed of it by SCO; all Linux kernel developers have considered this to be far too restrictive, so none of them have signed it. However, at SCO's annual reseller's convention in August of 2003 they revealed two short sections of code they alleged were copyright violations, and this code was later reprinted on the Heise website, a German computer magazine publisher.

On May 30, SCO Group's CEO Darl McBride was quoted as saying that the Linux kernel contained "hundreds of lines" of code from SCO's version of UNIX, and that SCO would reveal the code to other companies under NDA in July. [1] To put this into context, David Wheeler's SLOCCount estimates the size of the Linux 2.4.2 kernel as 2,440,919 source lines of code out of over 30 million physical source lines of code for a typical GNU/Linux distribution. Therefore, as per SCO's own estimate, the allegedly infringing code would make up about 0.001% of the total code of a typical GNU/Linux installation. [1]

SCO's major claims have now been reported as relating to the following components of the Linux kernel:

These claims flow from the accusation of breach of contract. The contract between IBM and SCO allows IBM to use SCO's SVR5 code, but the SVR5 code, plus any derivative works made from that code, must be held confidential by IBM. According to IBM's interpretation of the contract, "derivative works" means any works containing SVR5 code. But according to SCO's interpretation, "derivative works" also includes any code built on top of SVR5, even if that does not contain, or even never contained, any SVR5 code. Thus, according to SCO, any AIX operating system code that IBM developed must be kept confidential, even if it contains nothing from SVR5.

Free software community reaction

The lawsuit caused outrage in the free software and open source communities, who consider SCO's claims to be without merit. Open source advocates' arguments include:

SCO and its officers have been the subject of much criticism by the free software community, some of whom have stated that SCO's behavior may amount to illegal conduct. Indeed, SEC filings reveal that senior SCO executives dumped their personal holdings in SCO shortly after counter-suits were filed by IBM and RedHat, lending credence to the idea that the lawsuit's primary purpose is manipulation of SCO's stock price. SCO Group's CEO Darl McBride has been the subject of particular vituperation.

On May 30, Linus Torvalds was quoted by as saying, regarding the case:

"Quite frankly, I found it mostly interesting in a Jerry Springer kind of way. White trash battling it out in public, throwing chairs at each other. SCO crying about IBM's other women. ... Fairly entertaining."

In an interview on June 23rd, Torvalds responded to SCO's allegation that Linux development had no process for vetting kernel contributions:

"I allege that SCO is full of it, and that the Linux process is already the most transparent process in the whole industry. Let's face it, nobody else even comes close to being as good at showing the evolution and source of every single line of code out there."

The Inquirer reported on June 15, 2003, that an unnamed Linux kernel programmer has written to SCO, threatening action based on their distribution of a Linux distribution that, according to their own claims, contains code not licenced under the GPL. According to the letter reproduced there, the programmer claimed that SCO's doing so was an infringement of his own copyright. SCO's response to this letter is not known.

On June 25, Eben Moglen, the counsel for the Free Software Foundation, released a fuller statement regarding the SCO lawsuit. In this statement, he reiterates many of the points made above, and states that:

"As to its trade secret claims, which are the only claims actually made in the lawsuit against IBM, there remains the simple fact that SCO has for years distributed copies of the kernel, Linux, as part of GNU/Linux free software systems. [...] There is simply no legal basis on which SCO can claim trade secret liability in others for material it widely and commercially published itself under a license that specifically permitted unrestricted copying and distribution."

On July 31, the Open Source Development Labs released a position paper on the ongoing conflict [1], written by the FSF's Eben Moglen.

The GPL issue

Within a few months of the filing of the lawsuit, Eben Moglen, the Free Software Foundation's legal counsel, stated that SCO's suit should not concern Linux users other than IBM. In an interview with, he was reported as saying:

"There is absolute difficulty with this line of argument which ought to make everybody in the world aware that the letters that SCO has put out can be safely put in the wastebasket," ...

"From the moment that SCO distributed that code under the GNU General Public License, they would have given everybody in the world the right to copy, modify and distribute that code freely," ... "From the moment SCO distributed the Linux kernel under GPL, they licensed the use. Always. That's what our license says."

Apparently noticing the incongruity of their selling a Linux distribution while suing IBM for stealing their intellectual property and giving it to the developers of that operating system, the SCO Group then announced on May 14 that they would no longer distribute Linux. According to their press release, "SCO will continue to support existing SCO Linux and Caldera OpenLinux customers and hold them harmless from any SCO intellectual property issues regarding SCO Linux and Caldera OpenLinux products."

However, as of Monday, December 8, 2003, SCO Group was still distributing the Linux kernel under the terms of the GNU GPL via their FTP server. ( OpenLinux 3.1.1 linux-2.4.13-21S src.rpm [1] (FTP))

SCO currently claims:

Novell enters the controversy

Novell entered the controversy by publishing on May 28 a press release concerning the SCO Group's ownership of UNIX. "To Novell's knowledge, the 1995 agreement governing SCO's purchase of UNIX from Novell does not convey to SCO the associated copyrights," a letter to the SCO Group's CEO Darl McBride said in part. "We believe it unlikely that SCO can demonstrate that it has any ownership interest whatsoever in those copyrights. Apparently you share this view, since over the last few months you have repeatedly asked Novell to transfer the copyrights to SCO, requests that Novell has rejected."

SCO later claimed to have discovered an amendment to their contract with Novell transferring partial ownership to SCO. Novell stated that the amendment "appears to bear a valid Novell signature, and the language, though convoluted, seems to support SCO's claim that ownership of some copyrights for Unix did transfer to SCO"; Novell also said that it could not find its own copy of the amendment.

Fear, uncertainty and doubt

A number of Linux supporters have characterized SCO's actions as an attempt to create fear, uncertainty and doubt about Linux. Many believe that SCO's aim is to be bought out by IBM. Others have pointed to Microsoft's subsequent licensing of the SCO source code as a possible quid pro quo for SCO's action.

Univention GmbH, a Linux integrator, reported on May 30, 2003 it was granted an injunction by a Bremen court under German competition law that prohibits the SCO Group's German division from saying that Linux contains illegally obtained SCO intellectual property. If the SCO Group continues to express this position, they would have to pay a fine of 250,000 euros. A similar injunction was sought around the same time in Poland.

On July 23, Open Source Victoria announced that they had filed a complaint with the Australian Competition and Consumer Commission, "asking the ACCC to investigate the SCO Group's activities in light of their unsubstantiated claims and their extortive legal threats for money against possibly hundreds of thousands of Australians."

SCO Group then filed subpoenas for Richard Stallman and Linus Torvalds on November 13, 2003. [1]

Allegations of reverse copying

EWeek has reported allegations that SCO may have copied parts of the Linux kernel into SCO UNIX as part of its Linux Kernel Personality feature (see the EWeek report below). SCO has denied these allegations. Some open-source advocates have suggested that, if true, this may effectively have obligated SCO to release SCO UNIX source under the terms of the GPL to customers who have received SCO UNIX binary distributions.

IBM's AIX licence

Reuters reported that the SCO Group intended to revoke IBM's licence to use UNIX code in their AIX operating system on Friday, June 13 if no resolution is reached before then. IBM responded that they believe that SCO has no power to do so, as their license is "irrevocable". On the following Monday, June 16, CNET reported that SCO had announced it had terminated IBM's licence. IBM continues to distribute and support AIX, and the SCO Group now states that they will be seeking an injunction to force IBM not only to stop selling and supporting AIX, but to return to the SCO Group or destroy all copies of the AIX operating system.

Scheduler code claims

Also on June 15, postings on Slashdot and The Inquirer reported claims that:

Increased damages claims, and read-copy-update claims

As of June 17, CNET reported that SCO has increased its claims of damage to $3 billion, and has stated that the read-copy-update code in the Linux kernel is an example of code that infringes its rights. This technique is widely believed to have been developed at Sequent Computer Systems, who were then bought by IBM, who have been reported as holding several patents on this technique.

SCO announces that it will not sue its own customers

On June 23, SCO sent out a letter announcing that it would not be suing its own Linux customers. [1] In the letter, it states:

SCO will continue to support our SCO Linux and OpenLinux customers and partners who have previously implemented those products and we will hold them harmless from any SCO intellectual property issues regarding Linux.
Some observers have stated that in doing so, SCO may have granted the same rights to other Linux users who obtained a copy of Linux from an SCO partner under the terms of the GPL. Others have stated that to "hold someone harmless" is different from a grant of rights, and that SCO has not made a grant of rights in writing this letter. Others believe that this letter is moot, as a grant of rights was made by SCO by the act of releasing the software under the GPL in the first place. This action may also signal the grounds for a GPL violation suit against SCO as it is seeking different terms of distribution of works for its own customers than other recipients of the same work.

SCO to offer a "Linux licensing program"?

On July 21, 2003, SCO announced that it intends to sell binary-only licences to use the free Linux operating system which will remove the threat of litigation from licence-holders. Linux advocates reacted by stating that SCO has no basis for this action, and that doing this may cause SCO to forfeit their rights under the GNU GPL to distribute Linux or Linux-derived code in any form. Many commentators took the view that SCO had no legal basis for this, referring to wording in the GNU GPL that appears to explicitly prevent companies from doing this.

IBM points out SCO's GPL licensing of code

On July 28, it was reported that IBM was briefing its salespeople that SCO's distribution of Linux under the GPL appeared to undermine SCO's case.

Red Hat legal action and SCO's response

On August 4, 2003, it was reported that Red Hat has filed a legal action against SCO ([1], [1]). According to the filing, Red Hat has reqested that the court make:

SCO replied with both a press release and two letters to Red Hat on the same day ([1]); their claims are reiterated in the press release ("Linux includes source code that is a verbatim copy of UNIX and carries with it no warranty or indemnification. SCO's claims are true and we look forward to proving them in court."), and the allegations made by Red Hat are denied ("SCO has not been trying to spread fear, uncertainty and doubt to end users.")

The letters to Red Hat also hint at possible legal retaliations against Red Hat, saying:

"Of course, we will prepare our legal response as required by your complaint. Be advised that our response will likely include counterclaims for copyright infringement and conspiracy. I must say that your decision to file legal action does not seem conducive to the long-term survivability of Linux."

The Linux distributor SuSE, a member of the UnitedLinux consortium together with SCO Group, later expressed support for Red Hat's initiative, stating in a press release:

"SCO has already been halted in Germany and we applaud Red Hat's actions to help end their activities in the US -- and beyond. We applaud their efforts to restrict the rhetoric of the SCO Group -- and the FUD they are trying to instill -- and will determine quickly what actions SuSE can take to support Red Hat in their efforts." [1]

SCO announces licensing fees

One day later, on August 5 2003, SCO's Darl McBride announced the company's final licensing fees requested from end users for the use of Linux; a single-CPU server license will cost US $699 until October 15, 2003, and $1,399 afterward, while licenses for desktop and embedded systems will currently cost US $199 and US $32, respectively. Prices for server systems with more than one CPU range from US $1,149 for two CPUs to US $2,499 for four CPUs and US $4,999 for eight CPUs, with each additional CPU being priced at US $749. All of these prices, including the ones for desktop and embedded systems, are scheduled to be increased on October 15, 2003.

IBM counterclaims against SCO

On August 7, IBM filed their counterclaims against SCO. They make 10 counterclaims, including:

In response to these counterclaims, SCO has asserted that the GPL is unenforcible, void, and violates the United States Constitution. If these claims are true, then the GPL'd applications that SCO continues to distribute (like Samba) are being distributed without the permission of the copyright owners of those applications (since the permission was the GPL itself), which would be illegal. Thus some speculate that, in order to remain legally consistent, SCO will claim that software that has been GPL'd is actually in the public domain.


The discovery portion of the lawsuit has been dragging on for an unusual amount of time. The basis for SCO's suit is that any code developed on top of SVR5 is a derivative work of SVR5 (which would include AIX), and that IBM has publicly admitted to contributing AIX code to the Linux kernel. Since SCO has never seen the AIX code, it has, as part of the discovery process, deposed IBM for the AIX code, so that it can compare AIX code to Linux kernel code. IBM, rejecting SCO's concept of derivative work, has deposed SCO for which lines of code it claims are infringing. SCO has responded that it can't determine which code is infringing until it has had the chance to look at the AIX code.

Examples of controversial code revealed

New IBM counterclaims

On September 26, 2003 IBM filed new counterclaims against SCO Group involving alleged copyright infringement by SCO of GPL-licensed IBM code in the Linux kernel.

Some commentators have pointed out that if SCO manages to invalidate the GPL, they are highly likely to be caught by this counterclaim, as it is of the same form as their claim against IBM.

SCO acts against SGI

On October 1, 2003 the SCO Group announced that they would be revoking SGI's UNIX license for code it contributed to the kernel Linux. The source of this code was identified after it was shown at a reseller show.

First discovery hearing

On December 5, 2003, in the first oral arguments relating to the discovery process, a judge granted IBM's two motions to compel against SCO, and deferred consideration of SCO's motions until later. This gave SCO a 30 day deadline to provide "with specificity" which lines of code in Linux they claim form the basis of their case. This was widely regarded as a first-round victory for IBM.

Copyright claims, December 2003

In late December 2003, new developments involving copyright claims emerged.

Novell registered their claim to the copyright of original UNIX source code, effectively challenging SCO's registration of the same code. [1] [1]

SCO claimed in a press release to have sent DMCA notification letters alleging copyright infringement class="external">[1 Alleged copies of these letters were posted online at Groklaw and LWN. The letters give the names of 65 files in the Linux source code tree which supposedly incorporate "copyrighted binary interfaces". A rebuttal by Linus Torvalds was then posted on Groklaw.

External links

Press coverage

Please see SCO v. IBM Linux lawsuit: Press coverage for an extensive list of links to articles in various publications.


Commentaries, Opinions etc.



Other Resources

Note: Please note that none of the various claims made have yet been tested in court.