How can canceled matter from U.S. patent files be used as prior art?

While canceled matter is not a proper reference as of the filing date, it can still be used as prior art under certain conditions:

According to MPEP 901.01: “Matter canceled from the application file wrapper of a U.S. patent or U.S. application publication may be used as prior art as of the patent or publication date, respectively, in that it then constitutes prior public knowledge or prior public availability under 35 U.S.C. 102(a)(1) or pre-AIA 35 U.S.C. 102(a).”

This means that canceled matter can be considered prior art from the date the patent was issued or the application was published, as it becomes publicly available information at that point. Patent examiners and attorneys should be aware of this distinction when evaluating potential prior art during patent prosecution or litigation.

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