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For the manufacturing process setting, used for example in integrated circuit manufacture,, see Clean room.

For the meaning of Cleanroom engineering in software development, see Cleanroom Software Engineering.

Clean room design (also known as the Chinese wall technique) is the method of copying a design by reverse engineering and then recreating it without infringing any of the copyrights and trade secrets associated with the original design. Clean room design is useful as a defense against copyright and trade secret infringement because it relies on independent invention. However, because independent invention is not a defense against patents, clean room designs typically cannot be used to circumvent patent restrictions.

The term implies that the design team works in an environment that is 'clean', or demonstrably uncontaminated by any knowledge of the proprietary techniques used by the competitor.

Typically, a clean room design is done by having someone examine the system to be reimplemented and having this person write a specification. This specification is then reviewed by a lawyer to ensure that no copyrighted material is included. The specification is then implemented by a team with no connection to the original examiners.

Examples

A famous example is that of Columbia who built the first clone of an IBM computer through a clean room implementation of its BIOS. Another is VTech's successful clones of the Apple II ROMs for the Laser 128, the only computer model, among dozens of Apple II compatibles, which survived litigation brought by Apple Computer.

Another example of this technique is for designing the structure and operation of companies which have agreed to merge. In April 2005, SBC Communications and AT&T announced that independent business consultants were using clean room design techniques to develop recommendations for the structure and operations of their upcoming newly merged company. The work was kept secret until the companies closed on the merger deal; thereafter the results were presented to upper management. This approach allowed the companies to adhere to business laws (specifically antitrust legislation) while they were still competitors, but gave the newly merged company a head start in its structure and operations, when all legal rules have been satisified for the merger.

ReactOS has also used the clean room design technique in its attempt to create a clone of the Microsoft Windows operating system.