Lawyers for The SCO Group have declared that the GNU General Public Licence (GPL), under which Linux is distributed, is 'pre-empted' by the US Copyright Act.

SCO's lawyers, Boies, Schiller & Flexner, told vnunet.com that the US Copyright Act took priority over the GPL licence.

IBM's recent countersuit claims that SCO has violated the terms of the GPL.

"The GPL tries to define the rights of copyright holders with respect to copying, distribution and modification of copyrighted source code. These are activities covered by the [US] Copyright Act," the lawyer firm said.

"Article I of the [US] Constitution vests in congress the right to regulate copyrights. When congress enacted the Copyright Act, it defined certain exclusive rights that copyright holders can rely upon to protect their rights."

These rights include copying, authorising derivative works, modifying and distributing the copyrighted material, while an interest in copyrighted material cannot be transferred unless expressly authorised in writing, they said.

But in a question and answer document, Lawrence Rosen, a lawyer for the Open Source Development Lab which spearheads Linux development, said users faced little risk.

He predicted that SCO would have difficulty asserting its copyright claims.

Rosen said: "There will be a new open source version of Linux omitting any SCO code. Non-infringing Linux will be readily available for everyone's free use because the open source community is entirely committed to Linux," he said.

Rosen said copyright law is only imperfectly applied to software. "SCO has an even bigger hurdle to jump before it can assert its copyrights.

"Here's where the copyright aspects of this case will be a thrill for those of us who enjoy puzzles or metaphysics," he said.

He also dismissed the need for Linux users to have an indemnity, saying: "Assume, for example, that SCO wins its case and IBM pays $1bn in damages to compensate for the use of SCO's confidential code in Linux.

"How then could SCO turn to Linux users and ask for the same damages all over again? That double-dipping isn't fair in law or equity."

The full text of Rosen's Q and A can be found here.