What does 35 U.S.C. 121 say about patent validity and restriction requirements?
35 U.S.C. 121 includes a crucial provision regarding patent validity and restriction requirements. As quoted in MPEP 805:
“the validity of a patent shall not be questioned for failure of the Director to require the application to be restricted to one invention.”
This means that even if the USPTO did not require an applicant to separate multiple inventions into different applications, the resulting patent cannot be challenged on this basis alone. This provision protects patentees from post-grant challenges based on the USPTO’s administrative decisions during examination.
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