[2] The case holding that since the obligation to return unjust enrichment by performing the obligation to bear the expenses for the transfer of oil pipelines, which was borne by the motorway management agency as an additional official, on behalf of the other party, is only the legal obligation under the provisions of the Act, the commercial statutory interest rate under Article 54 of the Commercial Act cannot be applied to the damages for delay

"Liabilities arising out of commercial activities" to which the statutory interest rate in commercial activities under Article 54 of the Commercial Act applies includes not only obligations directly arising out of commercial activities, but also obligations similar thereto or obligations recognized as being modified.

However, according to the records, when it is necessary to transfer the pipelines laid underground due to the reasons such as the content of the burden as an assistant to be added to the defendant and its administrative disposition, namely, the expansion of the road, etc., on the premise that the management agency of the national expressway would take the beneficial administrative disposition of the site of the expressway against the defendant and the permission for the sale of the pipelines in the clearance zone, the plaintiff, as the management agency of the national expressway, is obliged to transfer the pipelines laid underground at the expense of the defendant, he determined in advance in the form of the agreement, and imposed an obligation under the agreement on the defendant as an assistant.

Thus, the defendant's liability for the relocation of oil pipelines is the duty that the plaintiff, as an administrative agency, caused by the subsidiary conduits attached to the permission while granting permission for the relocation of oil pipelines to the defendant. The plaintiff set the contents of the subsidiary conduits attached to the permission in the form of an agreement with the defendant, who is the other party to the administrative act, as the other party to the administrative act, cannot be deemed as the obligation arising from the commercial activity.

Therefore, even though the Defendant had a legal obligation to pay the relocation expenses by virtue of the subsidiary attached to the permission for the instant oil pipeline purchase, the obligation to return unjust enrichment of the instant case incurred by the Plaintiff in the course of paying the said expenses is merely the legal obligation arising under the provisions of the law, and cannot be deemed as a obligation identical to the obligation arising from commercial activities, or an obligation recognized as a modified obligation. Therefore, the statutory interest rate of commercial law under Article 54 of the Commercial Act as to the damages for delay

Nevertheless, the court below held that the statutory interest rate under Article 54 of the Commercial Act should be applied to the obligation to return unjust enrichment on the ground that the obligation to return unjust enrichment in this case constitutes the obligation identical to, or can be recognized as, that is identical to, the obligation arising from commercial activities. The court below erred by misapprehending the legal principles on the scope of application under Article 54 of the Commercial Act, thereby affecting the conclusion of the judgment.

Meanwhile, an application for restoration of provisional execution pursuant to Article 215(2) of the Civil Procedure Act is a kind of lawsuit during the lawsuit and its nature is a preliminary counterclaim. Therefore, inasmuch as the judgment of the court below is reversed after remanding the merits for the aforementioned reasons, the part of the order for restoration of provisional payment cannot be reversed after remanding.

Therefore, the defendant is obligated to pay to the plaintiff 522,378,000 won and damages for delay calculated at each rate of 5% per annum under the Civil Act from July 7, 2002 to May 31, 2003, and 20% per annum under the Act on Special Cases Concerning the Promotion, etc. of Legal Proceedings from the next day to the day of full payment. Since the part of the judgment below against the defendant ordering payment in excess of this is unlawful, the part of the judgment below is reversed. Since it is sufficient for the court to directly judge this part, it is decided to see Article 437 of the Civil Procedure Act. The judgment of the court of first instance corresponding to the above reversed part is revoked, and the plaintiff's claim corresponding to this part is dismissed. Since this part is sufficient for the court to directly judge this part, it is reasonable to dismiss this part of the judgment of the court below with the assent of all participating Justices 3,792,108 won and the remaining part of the judgment below as to the defendant's claim for provisional payment.

Justices Park Si-hwan (Presiding Justice)