Does an assignment need to be recorded to be effective?

An assignment of a patent does not need to be recorded with the Patent Office to be effective between the parties involved, as long as it is in writing. This means that the legal transfer of ownership rights can occur without the necessity of formal registration. While recording an assignment with the Patent Office can provide public notice and can be important for establishing priority against third parties, the assignment's validity and effectiveness are primarily contingent upon it being documented in a written form, indicating the intent of the parties to transfer rights. Therefore, the essential requirement is the written form of the assignment, rather than recording it with the Patent Office for it to have legal effect among the parties.