In United States patent law, the doctrine of inherency holds that, under certain circumstances, prior art may be relied upon not only for what it expressly teaches, but also for what is inherent therein, i.e., what necessarily flows from the express teachings.
The concept of inherency is predicated on the idea that a claim should not pass the test of anticipation merely because a feature of it is undisclosed or unrecognized in the prior art reference.
To establish inherency, the evidence must make clear that the missing matter is necessarily present in the prior art reference.
Once the United States Patent and Trademark Office (USPTO) establishes that a product referenced in prior art appears to be substantially identical, the burden shifts to the applicant to show a non-obvious difference.
"[2] A patent applicant may use the doctrine of inherency to respond to a rejection for lack of an adequate written description by showing that the patent application inherently includes the disclosure that is allegedly lacking.