If purchasing software were as straightforward as buying a car, users wouldn't have to think twice about the risk of intellectual property lawsuits. Say General Motors claims it owns a patent on power steering and alleges infringement by Ford. GM would have to sue Ford, not drivers who bought Ford cars, legal experts say.

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But software, unlike cars or most tangible consumer products, is licensed. Some software makers, particularly in the open source market, where code is often contributed by noncommercial developers from all over the world, use licenses to limit their liability and exclude user protection from intellectual property lawsuits. This protection would otherwise be implied by law, experts say.

"People who buy software have less protection than people who buy cars," says Bruce Sunstein, a patent attorney at Bromberg & Sunstein in Boston. "The license terms have been designed to protect software vendors."

Underscoring a growing awareness of this issue on the part of users, Microsoft earlier this month expanded its intellectual property indemnification program to cover most of its customers. Previously the company covered only so-called volume license buyers - customers who buy Microsoft's products in bulk. The Microsoft plan protects customers from exposure to legal costs and damages related to patent, copyright, trade secret and trademark claims. The protection has no financial cap.

With the expanded program, Microsoft is seeking to set itself apart from rivals, especially those in the open source community. Users are showing more interest in indemnification programs, particularly for Linux after The SCO Group, which says Linux includes some of its copyright-protected code, earlier this year threatened infringement lawsuits.

Protection plans

The type of protection software indemnification programs offer varies widely. Vendors typically offer comprehensive protection for proprietary products, but not for open source software. Novell offers SuSE Linux Enterprise Server 8 customers protection against copyright-infringement claims only. The protection also is capped and tied to restrictions such as the requirement to purchase a maintenance contract. HP offers indemnification for Linux products it sells, but only against SCO claims, and the buyer must sign a support contract and use HP hardware. Linux vendor Red Hat does not indemnify customers, but promises to replace Enterprise Linux code for users if a court were to find that the product infringes a copyright. IBM does not indemnify the Novell and Red Hat Linux products it sells. Sun says it offers indemnification for all Sun-branded software, but failed to provide details of its programs by press time.