When can canceled matter in a patent application be considered prior art?

Canceled matter in a patent application is considered prior art as of its patent or publication date. This principle arises from the understanding that once a patent application is published or issued, the details contained within it, including any canceled claims or matter that was part of the application, become publicly accessible and can potentially influence the novelty and non-obviousness assessments of subsequent patent applications.

When a patent application is filed, it may undergo amendments and cancellations before either being granted or published. The information disclosed in the application—regardless of whether it remains in the final granted claims or is canceled—can still serve as prior art as of the date that the application itself is made publicly available, which typically occurs upon publication or issuance. This reflects the policy intention to ensure that the knowledge contained in patent documents is available to the public, thereby preventing any assumption of novelty for similar inventions filed afterwards.

Considering this context, the assertion that canceled matter can only be considered prior art as of its filing date is incorrect since prior art status is more appropriately assigned to the later date of publication or patent grant, which is when the public can access said information.