Software Defect Classes and No-fault Liability

Software is increasingly used to control systems that can cause harm to the consumer. There is consensus among commentators that many software systems are “products” for purposes of the law of products liability. However, strict products liability in tort has yet to be applied to software products. The day is certainly coming. The Restatement of the Law, Third, Products Liability, explains that the legal standard for defect in design is based in negligence, while the standard for defect in manufacturing is strict. Expected costs for software developers are higher for defects in manufacture because “due care” provides no defense under the strict standard. The mere existence of the defect that causes injury will trigger liability for damages. Software defects have not yet been characterized relative to these categories. The necessary characterization of defects depends on the existence of an algorithm that can distinguish product design from manufacture; deliberate engineering decisions from nondeliberative activities in implementing the design. Solution is sought by analogy to working algorithms used in traditional engineering domains. Due to some properties fundamental to software, no such algorithm can be found. Neither legal nor software engineering notions of defect present workable alternatives.