What happens if the best mode is not disclosed before the filing of a patent application?

The best mode requirement pertains to a patent applicant's obligation to disclose the preferred way of practicing the invention at the time of filing. However, failure to disclose the best mode does not automatically invalidate the patent application or prevent it from being granted. The application can still claim priority from an earlier-filed application as long as it satisfies the other patentability requirements, such as novelty and non-obviousness.

Claiming priority means that if the earlier application disclosed the invention and was filed first, the later application can benefit from the filing date of the earlier application. This is separate from the best mode requirement, which, while important, does not affect the ability of the applicant to maintain priority for the claims. Therefore, even if the best mode is not disclosed, the application remains intact regarding its priority status.

The other options aren't correct within the context of patent law. The application is not automatically deemed invalid solely for failing to disclose the best mode, nor does the absence of such a disclosure prevent the patent from ever being granted—this is a common misconception. Additionally, while a patent can be reissued, this is not a straightforward solution designed for best mode issues and requires specific conditions regarding errors in the original patent rather than mere lack of disclosure.