A coloquial expression often used to describe the, usually dayglo orange, flight recorders mandated by the International Civil Aviation Organization for civil airliners that can be inspected, especially after an accident to help determine its causes.
However, the expression is also used in technology to describe a component or device that is supplied by a vendor to another company, for example a manufacturer, with a simple specification describing what it does, how it connects or interfaces, but little or nothing about its internal workings – how it does what it does. A black box can be a serious problem in litigation, especially patent litigation, since the immediate defendant may not be able to say whether it infringes or not. Compounding this problem, some vendors are extremely unwilling to offer any technical or litigation support – which is why it is wise to build litigation support obligations into supply agreements.