Under the AIA, how strict is the requirement for disclosing "the best mode" in an application?

Under the America Invents Act (AIA), the requirement to disclose "the best mode" is not strict in terms of invalidating an application. The best mode requirement originally mandated that an inventor must disclose the preferred and optimal way of carrying out their invention. However, the AIA shifted the focus away from this requirement, meaning that a failure to disclose the best mode does not render an application invalid. Instead, it can be considered more of a formal requirement rather than a substantive one that directly affects the patentability of the claims.

This means that while it's still advisable to disclose the best mode in order to satisfy the spirit of the patent laws and enhance the quality of the patent, the absence of such a disclosure will not result in rejection of the application or invalidation of a granted patent. This relaxation of the requirement reflects a broader shift towards easing the burdens of compliance for inventors in the patent process.