What consequence might arise if a rule does not adhere to the federal law deadline?

When a rule does not adhere to the federal law deadline, it may be deemed invalid. This situation arises because the law generally requires that any regulations established must comply with specified timelines set forth in federal guidelines. If a rule is proposed or finalized outside of these deadlines, it is not recognized as valid or enforceable, thus rendering it ineffective for legal or operational purposes. This principle ensures that regulatory processes maintain their integrity and that stakeholders are protected by having rules that comply with established legal frameworks.

In contrast, the other choices described do not align with the direct consequences of failing to meet federal law deadlines. Ignoring the rule does not reflect the legal reality, as the rule would still exist but not be enforceable. Closing public hearings is not directly tied to adherence to deadlines and generally pertains to procedural aspects of rule-making. Similarly, the idea that a rule would be immediately enforced despite being outside of the legal timelines contradicts the foundational requirement that compliance with deadlines is essential for a rule's validity. Thus, the option stating that the rule may be deemed invalid rightly captures the legal implications.