现代国际关系中，经济制裁逐渐成为对外政策的重要工具。制裁发起方通过实施一系列强制性经济举措，旨在迫使目标国家乃至第三方国家调整其政策及行为。在此框架下，原本不受政治因素直接影响的私人商贸活动也被迫纳入了严格的监管范围之内。经济制裁不仅直接妨碍合同一方履行交付货物或资金支付结算的能力，其连锁反应还可能渗透至整个供应链，波及合同双方乃至更广泛的商业伙伴，从而触发国际货物买卖合同履行障碍。当一方坚持合同继续执行而另一方因经济制裁影响违约并提出履行困难时，纠纷便在所难免。《联合国国际货物销售合同公约》（CISG）是普遍适用、广泛认可的公约，其第79条关于障碍免责条款为经济制裁下的合同当事人提供了不可抗力免责空间。透视经济制裁下CISG第79条的适用问题为实践具体应用提供更多参考。

经济制裁如何构成CISG第79条“障碍”是适用的关键问题。在合同自身未明确约定不可抗力条款或条款表述不清晰的情况下，需依据CISG的框架评估经济制裁是否满足“障碍”的三个法定要件：不能控制、不能预见以及不能避免或克服。尽管经济制裁通常满足“不能控制”要件，但其是否符合其余两个要件则需更深入地分析。其中，对于“不能预见”的判断标准应适当放宽，旨在确保对合理预见范畴的评估体现公正性，同时依据具体情境分析支付或交货面临的障碍是否达到了“无法克服或避免”的标准。在认定经济制裁是否构成“障碍”要件的基础上，经济制裁应如何构成的细节问题需要进一步讨论。鉴于经济制裁往往造成的是“履行困难”而非绝对“履行不能”，故应采取相对不能的障碍程度性标准。涉及合同外第三方的合同争议中，识别“第三方”身份以及双重障碍的判定标准为直接引用CISG第79条第2款带来挑战。此时，当事人可能转而依赖第79条第1款，但需更加细致地论述当事人风险承担范围。

适用CISG第79条还需要关注当事人的通知义务、举证责任的分配，以及成功援引障碍免责条款后当事人的合同救济义务。违约方及时履行通知义务，按照构成障碍的要件和因果关系进行举证，有利于降低损失、增加成功免责的可能性。经济制裁被认定为障碍后，不仅违约方可以免除损害赔偿责任，基于合同公平和交易稳定，合同当事人可以在艰难情势下请求重新协商和请求法院变更合同，避免陷入僵局。

In the contemporary landscape of international relations, economic sanctions have progressively emerged as a pivotal instrument of foreign policy. The imposing party enforces a gamut of coercive economic measures, all aimed at compelling targeted states and even third-party nations to recalibrate their policies and conduct. Consequently, private commercial activities, hitherto insulated from direct political influence, find themselves ensnared within stringent regulatory frameworks, rendering the environment for executing international sales contracts highly intricate and mutable. This scenario not only directly impedes one party's ability to fulfill delivery obligations or settle financial payments but also disseminates a ripple effect across supply chains, implicating both contractual parties and an extensive network of commercial associates, thereby triggering obstacles to contract performance. In instances where one party insists on contract execution while the other cites economic sanctions as a hindrance to fulfillment, disputes become inevitable. Thus, the defaulting party often seeks recourse in the doctrine of force majeure.

The United Nations Convention on Contracts for the International Sale of Goods (CISG), a universally applicable and widely endorsed treaty, furnishes its Article 79 as a provision that affords exemption space for contracting parties under the shadow of economic sanctions. Where contracts lack explicit clauses on force majeure or bear ambiguous formulations, reliance is placed upon CISG’s framework to assess whether economic sanctions satisfy the three statutory elements of an "impediment": namely, uncontrollability(beyond one’s control), unpredictability(could not reasonably be expected to have taken the impediment into account), and insurmountability or unavoidability(could not avoided or overcome). While economic sanctions typically conform to the criterion of "uncontrollability," further scrutiny is required to ascertain their adherence to the remaining two criteria. Here, the standard for assessing "unpredictability" should be moderately relaxed to ensure a fair and practical evaluation of what could reasonably have been foreseen, with specific circumstances determining whether payment or delivery obstructions meet the threshold of being "insurmountable or unavoidable." Moreover, a nuanced discussion is necessitated regarding the specifics of how economic sanctions constitute an "impediment," especially considering that they tend to engender "performance difficulties" rather than absolute "impossibility," thus warranting a relative standard for assessing the degree of impediment. In contract disputes involving third parties, identifying the "third party" and applying the dual obstacle criteria pose challenges to invoking CISG Article 79(2), potentially steering parties towards reliance on Article 79(1), albeit with a more meticulous delineation of risk-bearing responsibilities.

Implementing CISG Article 79 also necessitates attention to the parties' notification duties, the apportionment of the burden of proof, and the contractual relief obligations of a party successfully invoking the exemption clause for obstacles. Prompt fulfillment of notification obligations by the defaulting party, along with evidence presentation adhering to the elements and causality of the impediment, facilitates loss mitigation and enhances the likelihood of successful exemption. Upon recognition of economic sanctions as an impediment, not only can the defaulting party be relieved from liability for damages, but, in the interest of contractual fairness and commercial stability, the parties may petition for renegotiation or seek judicial modification of the contract, thereby averting a deadlock.