The companies jointly sent a expressing their common disagreement with advice regarding software law that a group plans to send to judges.

The American Law Institute (ALI), an association that develops documents meant to help guide judges as they make decisions on complicated legal subjects, is presenting a final draft of its guidelines for software contracts on Tuesday during its annual meeting. The document has been in the works since 2004 and if it is approved it will be published.

Despite the differences that most often divide Microsoft, which relies on proprietary software sales for its lifeblood, and the Linux Foundation, which promotes open-source software, the two agree in this situation.

They urge the ALI specifically to clarify a section of its document that concerns warranties on defects in software. The document appears to absolve commercial open-source software from the types of warranties that would be applied to proprietary software. But because many open-source software providers make money, such as through advertising, it's unclear if such providers would be liable for defects according to the document.