When can an authority apply portions of the code retroactively?

The correct answer is rooted in the idea that retroactive application of certain codes or regulations is necessary to address immediate threats that may pose a risk to health, safety, or the environment. When there is an immediate threat of hazard, authorities may need to act quickly to safeguard the public. This urgency justifies the retroactive application of the code to ensure compliance with safety standards and to mitigate risks as soon as possible.

In contrast, filing a complaint or conducting government inspections does not inherently justify the retroactive application of code provisions, as these actions are often part of the standard process for compliance or regulation without an urgent threat. Additionally, applying a code retroactively simply because it has been updated might not align with legal or regulatory frameworks, which usually dictate that changes apply going forward unless an exception for immediate safety concerns exists. Therefore, the ability of an authority to apply portions of the code retroactively is fundamentally linked to the necessity of addressing severe risks promptly.