Under what condition must legal action be commenced according to the discoverability principle?

The discoverability principle in law specifically pertains to the timeframe within which a plaintiff can initiate legal action based on the discovery of a defect or a cause of action. According to this principle, the clock starts ticking from the moment the injured party becomes aware, or ought to have become aware, of the defect or the damage caused by a specific issue.

In this context, the correct answer states that legal action must be commenced within 2 years of discovering a defect. This timeframe is significant as it grants the injured party a reasonable period to investigate and assess the nature of the defect before taking legal action. This principle also ensures that claims are made while evidence and witnesses are still relatively fresh, which is essential for a fair and just resolution to legal disputes.

The other options outline timeframes that do not align with the standard requirements outlined by the discoverability principle. For instance, initiating legal action within 30 days or 6 months is typically too short to allow an affected party to fully understand or evaluate their situation after discovering an issue, while the 15-year option might exceed reasonable limitations based on the nature of many defects, which usually call for a more urgent response.