Principle: Any person or business knowingly aiding someone' s infringement on a copyright is also guilty of copyright infringement
Application: Grandview Department Store, which features a self-service photo-printing kiosk, is guilty of copyright infringement since a customer using the kiosk infringed on a wedding photographer' s copyright by printing photographs whose copyright is held by the photographer
A person or business providing a service that can be expected to be used to infringe on a copyright should be considered to knowingly aid any copyright infringer using the service.