The right of action for contributory infringement of a patent was forged by judicial legislation, and, as limited and subjected to opposing rules of law, has been tempered by that same process. The history is exemplary of the control over society exercisable by the courts according to their own individual economic outlook.

In tracing this history, buying agreements, price-fixing, agreements not to deal in the goods of a competitor, conspiracies to restrain trade through licensing, and other business arrangements subject to scrutiny under the anti-trust laws will be dealt with only incidentally. It is not possible to deal only with combination patent cases in presenting a fair and accurate record of what has transpired. But since that patent was instrumental in giving rise to the doctrine of contributory infringement, and has consequently suffered the most in its limitation, it will receive predominate treatment.