“未预见的发展”是GATT第19条设定的保障措施实施条件之一,与条约法上的“情势不变条款”既有相同之处,也有明显差异。《保障措施协议》与GATT第19条并不存在冲突,故该条款不能被取消适用;相反,按照有效解释原则,该条款应被赋予实质意义。该条款是指成员方在关税减让谈判时所未预见的之后的情形。在WTO争端解决实践中,该条款实际上是作为一项独立条件予以适用的。WTO成员方在实施保障措施之前,必须对该条款予以证明。 “Unforeseen developments” is one of the conditions for the implementation of the safeguards set forth in Article 19 of the GATT. There are both commonalities and significant differences with the “unchanged conditions” in the law of treaties. The Safeguards Agreement does not conflict with Article 19 of the GATT and therefore the provision can not be de-applied; on the contrary, the provision should be given substance in accordance with the principle of effective interpretation. This clause refers to the situation after the member has not been foreseen at the time of the tariff concession negotiation. In the WTO dispute settlement practice, the clause is actually applied as an independent condition. WTO members must implement the safeguard measures before this clause must be proved.