A more thorough explanation:

Substantial noninfringing use refers to the routine use of a product in a way that does not violate intellectual property rights. It is a legal test used to determine whether the sale of a product amounts to contributory infringement.

For example, a video recorder can be used to record a program and watch it later without infringing on any intellectual property rights. Therefore, the sale of video recorders cannot be stopped, and the manufacturer cannot be subjected to a court-imposed royalty.

The Sony Corporation of America v. Universal City Studios, Inc. case established the Sony doctrine, which states that if a product has a substantial noninfringing use, then its sale cannot be stopped. This doctrine protects manufacturers from being held liable for contributory infringement if their products have a legitimate noninfringing use.

Another example of substantial noninfringing use is the sale of blank CDs. While they can be used to make illegal copies of copyrighted material, they also have a legitimate use in creating original content or backing up personal data.

Overall, substantial noninfringing use is an important legal concept that helps balance the protection of intellectual property rights with the freedom to use products in legitimate ways.