Characteristics of imperfect performance liability causes defect of goods are as follows: A breach of main performance obligation by the obligor happens to violate payment interest, and thus results in extended damage of integrity interest of the creditor. Compensation accruing to the typical sales contract of civil law, it is regulated that warranty against defects liability and nonperformance of obligation should be applied in Korean civil law. Generally, warranty against defects liability have it as its normative principle to immediately recover the imbalance of equivalent exchange value. Therefore, since it is liability without fault, scope of indemnity should be duly limited to reliability interest. But it shouldn't apply to extended damage.
To cut it short, the adjustment of extended damage should be applied to the concept of nonperformance of liability in §390 (Korean Civil Law). The legal bases of this legal interpretation is that the seller has recognized the defect of his or her merchandise or has failed to inform the buyer out of mistake. That is to say, the seller has neglected to fulfill notification duty of good faith. Thus, warranty liability should be applied to the damage due to the defective goods, and extended damage should be covered under the concept of imperfect performance liability. And these two legal concepts should bid against each other (inter-pleader action).
The traditional legal concepts of contract liability and tort-law liability in civil law cannot assure fair and equitable solutions of legal cases in the event that defective commercial products result in extended damage. Therefore, those cases should be covered under the product liability law. The application of this law, however, should be performed in favor of consumers, who tend to be in a lesser position as parties involved in contracts.