SCO's controversial court case against IBM in which it claims Linux uses copyrighted Unix source code has been comprehensively chewed up online by the Open Source Initiative.

The non-profit organisation has produced a lengthy critique of the court filings with heavy supporting evidence and posted it in its Halloween documents section - something previously dedicated to furious debunking of Microsoft.

Written by computer programmer, Linux lover and erstwhile journalist Rob Landley and reviewed by the president of OSI Eric Raymond, the critique explains the complex history of Unix and Linux development in a bid to undermine SCO's claims.

The credibility the document loses in its partisan approach is mostly recovered through the use of hyperlinks to extensive supporting evidence. However, while much of it is rightly dedicated to proving that SCO does not have possession of the copyright and trademarks it claims to, its greatest strength lies in other arguments.

That OSI disagrees with SCO over its rights is hardly surprising and that is the very reason for a court case - in order that a judge may ascertain who is right in their claim. However, it may very well be that the case is dismissed without regard to this main argument due to SCO's inconsistent approach to Linux.

As is made abundantly clear in the OSI document, SCO actively worked with the Linux community for years, even producing its own versions of Linux. It included Linux filings to the US Securities and Exchange Commission. It signed up to the GNU General Public Licence. In August 2001, Caldera CEO Ransom Love (Caldera was previously SCO) was quoted as saying: "Caldera is absolutely committed to open source."

All this somewhat undermines SCO case. A judge would be perfectly entitled to ask how come is that SCO is now threatened and damaged by the use of Linux when it previously aided the operating system's development.

As perhaps the strongest argument away from the copyright/trademark issue is the SCO never made any formal complaint or brought any legal action against Linux despite it being developed in the open since 1991. The very lifeblood of Linux is the fact that its source code is available for anyone to review.

All that need be argued and pointed out is the SCO attempted to profit from Linux yet never achieved a good foothold in the market. Any reasonable judge could then be expected to write off the court case, regardless of the complex dispute surrounding who owns what part of Unix. A judge would also bear in mind the likely effect of allowing a legal victory over parts of a source code (Unix) that has been so widely used across so many different platforms in the past few decades.

But then of course, this case is only part about trying to win and very much about shaking companies' growing confidence in the licence-free open source OS. The dark hand of Microsoft is very close to this one.

This document however should put some of that confidence back. Although a more objective and less emotive version would do the job far better.