If the law did not work that way, then the GNU GPL would not be enforceable.
The GPL for example required that if I distribute a derivative of a GPLed work in binary form, then I must also distribute the same derivative as source code or at least provide the source code to any distributee who asks for it. This requirement of the GPL has been enforced by courts (e.g., in a lawsuit against Tivo) even though none of the defendants in these court cases signed a contract regarding the use of the software.