ElectronicjournalofcomparatiVeLaw,vol.8.1(march2004),<http://www.ejclorg/> occur even beyond those borders. 2I The illustration of the risk sphere, however, must not be taken literally. It is also beyond a debtor's control if the debtor's factory is destroyed by a terrorist attack, 22 even if the terrorist entered the factory itself. The third requirement is that it could not reasonably have been expected to take the impediment into account at the time of the conclusion of the contract. Either the party should have accepted the risk or have been at fault in not having foreseen it. 3The stand reasonable foreseeability24 jud ged from the perspective of a normal person placed in the same situation. The party should not be too anxious, but if an obstacle is reasonably foreseeable and the debtor nevertheless contracts uncond itionally, he has taken the risk that the Fourth, it is required that it could not reasonably have been expected to have avoided or overcome the impediment or its consequences. The commentary summarises this issue as the impediment being "insurmountable >This prerequisite may be surprising. As the imped iment must be outside the partys control, how could the party have avoided it? The PECL's commentary illustrates: In an earthquake zone the effects of earthquakes can be overcome by special construction techniques, though it would be different in the case of a quake of much greater force than usual. 26 But demand ing an earthquake-resistant construction presupposes that the risk has been foreseen or was foreseeable. In many cases, the prerequisite of a non-foreseeable imped iment steps in. The issue whether an imped iment is insurmountable is hence only rarely relevant. E. g. where the risk was not foreseeable originally -i.e. at the time of the conclusion of the contract -but becomes foreseeable afterwards or where the obligation can be fulfilled in a different way -e.g. in a contract for the delivery of goods that under normal circumstances would be delivered by sea -the imped iment is not irresistible if transfer by air is possible, generally, if there commercially reasonable substitute available. 28 The obligator is required to incur extra Intentional interference by the debtor (unlike culpable action) is not necessarily covered by the standard sphere of responsibility. The delayed performance example provided by the commentary is a special case, because the event that constitutes the impediment may nevertheless be an extermalone. Yet, the fault on the part of the debtor allowed the external event to have its effect on the performance Cf for Art 79 CISG Schlechtriem/Stoll, n 16, Art 79 para 20 Lando/Beale, n 2, 380(comment c(i) Lando/ Beale, n 2, 381(comment c()); cffor Art 79 CISG: Bianca/Bonell/Tallon, n 16, Art 79 para 2.6.3; F Enderlein, F Maskow, D Strohbach(eds), International Sales Law(1992), art 79, para 5.3 Schlechtriem/Stoll, n 16, art 79 para 23 Lando/Beale, n 2, 381(comment c(il)) This illustration is more appropriate for the question of foreseeability. It shows that, although a risk of a specific kind is foreseeable, e.g an earthquake, an earthquake of a strength that could not have been reasonably expected is not foreseeable Nicholas n 12.24 ForArt79Cisg,SecretariatCommentaryArt65,para7ff<http:/www.cisg-online.ch/cisg/materials commentary.htmp,OlgHamburg,28February1997,CisgoNline261<http:/www.cisg- online.ch/cisg/urteile/261. htm>, Schlechtriem/Stoll, n 16, art 79 para 24Electronic Journal of Comparative Law, vol. 8.1 (March 2004), <http://www.ejcl.org/> 5 occur even beyond those borders.21 The illustration of the risk sphere, however, must not be taken literally. It is also beyond a debtor’s control if the debtor’s factory is destroyed by a terrorist attack,22 even if the terrorist entered the factory itself. The third requirement is that it could not reasonably have been expected to take the impediment into account at the time of the conclusion of the contract. Either the party should have accepted the risk or have been at fault in not having foreseen it.23 The standard is one of reasonable foreseeability24 judged from the perspective of a normal person placed in the same situation. The party should not be too anxious, but if an obstacle is reasonably foreseeable and the debtor nevertheless contracts unconditionally, he has taken the risk that the impediment evolves. Fourth, it is required that it could not reasonably have been expected to have avoided or overcome the impediment or its consequences. The commentary summarises this issue as the impediment being ‘insurmountable’.25 This prerequisite may be surprising. As the impediment must be outside the party’s control, how could the party have avoided it? The PECL’s commentary illustrates: ‘In an earthquake zone the effects of earthquakes can be overcome by special construction techniques, though it would be different in the case of a quake of much greater force than usual.’26 But demanding an earthquake-resistant construction presupposes that the risk has been foreseen or was foreseeable. In many cases, the prerequisite of a non-foreseeable impediment steps in. The issue whether an impediment is insurmountable is hence only rarely relevant. E.g. where the risk was not foreseeable originally - i.e. at the time of the conclusion of the contract - but becomes foreseeable afterwards or where the obligation can be fulfilled in a different way - e.g. in a contract for the delivery of goods that under normal circumstances would be delivered by sea - the impediment is not irresistible if transfer by air is possible;27 generally, if there is a commercially reasonable substitute available.28 The obligator is required to incur extra 21 Intentional interference by the debtor (unlike culpable action) is not necessarily covered by the standard sphere of responsibility. The delayed performance example provided by the commentary is a special case, because the event that constitutes the impediment may nevertheless be an external one. Yet, the fault on the part of the debtor allowed the external event to have its effect on the performance. 22 Cf for Art 79 CISG Schlechtriem/Stoll, n 16, Art 79 para 20. 23 Lando/Beale, n 2, 380 (comment c(ii)). 24 Lando/Beale, n 2, 381 (comment c(ii)); cf for Art 79 CISG: Bianca/Bonell/Tallon, n 16, Art 79 para 2.6.3; F Enderlein, F Maskow, D Strohbach (eds), International Sales Law (1992), art 79, para 5.3; Schlechtriem/Stoll, n 16, art 79 para 23. 25 Lando/Beale, n 2, 381 (comment c(iii)). 26 This illustration is more appropriate for the question of foreseeability. It shows that, although a risk of a specific kind is foreseeable, e.g. an earthquake, an earthquake of a strength that could not have been reasonably expected is not foreseeable. 27 Nicholas, n 12, 24. 28 For Art 79 CISG, Secretariat Commentary, Art 65, para 7ff <http://www.cisg-online.ch/cisg/materials￾commentary.html>; OLG Hamburg, 28 February 1997, CISG Online 261 <http://www.cisg￾online.ch/cisg/urteile/261.htm>; Schlechtriem/Stoll, n 16, art 79 para 24