What is the purpose of 35 U.S.C. 121 in relation to double patenting?
The purpose of 35 U.S.C. 121 is to protect inventors from double patenting rejections that might arise due to administrative requirements imposed by the USPTO. As explained in the MPEP, citing Applied Materials Inc. v. Advanced Semiconductor Materials:
“[W]hen the existence of multiple patents is due to the administrative requirements imposed by the Patent and Trademark Office, 35 U.S.C. Section 121 provides that the inventor shall not be prejudiced by having complied with those requirements. Thus when two or more patents result from a PTO restriction requirement, whereby aspects of the original application must be divided into separate applications, Section 121 insulates the ensuing patents from the charge of double patenting.”
This provision ensures that inventors are not unfairly penalized for complying with restriction requirements and filing divisional applications. However, this protection is subject to certain conditions, such as maintaining consonance with the original restriction requirement.
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