Waleed Mahmoud Elfarrs, is an Egyptian lawyer; Teaching and Research Associate at the Kalshoven-Gieskes Forum, Leiden University; and Founder of The Legalist.


Contemporary armed conflicts are characterized by their proximity to urbanization, as opposed to most of the 18th and early 19th Centuries’ armed conflicts, where warring parties engaged in deserts or high seas. In this connection, international scholars are, and should be, increasingly concerned with the legality of ancient naval method of blockades as conducted in today’s armed conflicts (see here, here, here and here). The presumed legal status quo of blockades is that they are not per se unlawful under international law. However, this post attempts to demonstrate the likelihood that this may no longer be the status quo of international law on the lawfulness of blockade. Relying on the situation in Yemen, I argue that blockades are likely to be referring to an all-encompassing conduct that is likely to be inherently unlawful under International Humanitarian Law (IHL). Hence, an IHL treaty law on blockade is required. Until then, this post proposes that a preponderance regarding the lawfulness of a blockade cannot be merely established on the basis of the law of neutrality, and without assessing under IHL rules and principles every individual method, tactic or conduct in furtherance of that blockade.

The International Legal Framework Applicable to Blockade:

As is commonly known among international law scholars and practitioners, the task of identifying the legality of blockades is complicated as there is neither a directly binding international document nor an established custom which determine the legality of blockade, especially in relation to humanitarian exigences. However, the rather fragmented framework of international law consists of various legal regimes that are applicable to blockades. Two of which are strictly relevant to blockades during armed conflict: (1) the law of neutrality (also here); and (2) IHL.

  1. The law of neutrality: balancing between belligerent rights and neutral rights:

Drawing on available definitions, a blockade can be defined as an operation involving naval (and now land and air forces) by which a belligerent prevents the movement from or to a (land, coastal and air) port belonging to an enemy. The purpose of blockades is to block any supplies to the adversary. The law of neutrality recognizes blockades as such, and accordingly regulates the relation between belligerent parties and neutral parties to armed conflicts (Bothe, 532). In this vein, the belligerent is not prohibited from blocking vessels and aircrafts from entering and exiting specific areas, and from hindering supplies, war materials or communication from reaching that area. In contrast, the neutrals are assured some rights e.g., the safety of neutral vessels, safe passage, undisturbed commerce with non-belligerents, etc.

Although there are no binding international treaties on blockades to back up the above reading to blockades, there are references to blockades in a number of international documents, military manuals, and scholarly writings such as the Paris Declaration of 1856, the London Declaration of 1909, and the San Remo Manual of 1994.  According to these documents, there is a tripartite criterion that governs neutral relations when conducting blockades. They establish that parties conducting blockades must (1) notify neutrals about their blockades; (2) impose an ‘effective’ blockade; and (3) deal impartially with neutrals (See generally, here and here).

  • International humanitarian law: balancing between military necessity and humanity:

In regulating the conduct of hostilities, including the conduct of blockades, IHL seeks to balance between military necessity and humanity. This balance is reflected in the cardinal principles of distinction, proportionality, and precaution, which in turn underline the more concrete IHL norms as stipulated in the Geneva Conventions (GCs), the Additional Protocols (APs), the ICRC Customary IHL and national (also here) and international and other documents. In these documents, there are general principles that are applicable to all means and methods of warfare used in armed conflict, including blockades  such as the overarching principle establishing that the use of means and methods of war is not unlimited( as well as specific IHL norms that are applicable to blockades (e.g., Articles 3 of GCs; 54(1), 49(3), 69 and 70 of API; and 14 of APII).

  • The methodology of applying two legal regimes under international law:

Applying the methodology of the ILC study 2006 on the fragmentation of international law, it is evident that the law of neutralitywould act as lex generalis as opposed to the more concrete lex specialis norms of IHL as regards blockades imposed in situations of armed conflict. To say that, the legality of blockades cannot be merely determined on the basis the law of neutrality irrespective of IHL. Indeed, until a specific treaty is concluded, or a custom emerges on blockades, the applicable norms of IHL will apply as they apply ipso facto to any situation involving an armed conflict. Therefore, there is no such thing as legal or illegal blockade when factoring in IHL. Under IHL, a blockade as an umbrella tactic is not considered lawful or unlawful, but each concrete tactic or method which contributes to a given blockade, and its conformity to the rules of IHL, is to be examined separately.

Reflections on the Law on Blockade, and the Blockade of Yemen:

Background on the situation in Yemen:

The situation in Yemen remains by far the largest humanitarian crisis in the world for the third year running, with more than 24 million people in dire need of humanitarian assistance (here, here and here). In 2019 and 2020, Yemen stood vulnerable against the spread of the cholera epidemic and the COVID-19 pandemic, without agriculture, food, water, fuel, sanitation, and healthcare systems (see here and here). Today, the FAO, WFP, and UNICEF are warning that famine conditions in Yemen will increase threefold in the first six months of 2021. Such a disastrous situation is often traced back to the conduct of blockading in Yemen since 2017. Since then parties to the Yemeni conflict have imposed devastating blockades, and impeded or taxed humanitarian assistance. Furthermore, they hampered companies’ access to supply local markets with food, medicine, and necessities or imposed double taxation (i.e., punitive blockade). Although a major blockade on Yemen has been publicly “lifted” since 2017 due to pressure by the UN, a de facto blockade remains in place (see e.g., here and here), while funding and donations directed to Yemen are hopelessly declining.

United Nations’ approaches concerning the legality of blockade in Yemen:

In Yemen, and with failed peace talks by the UN, and as the Houthi insurgents and the Saudi-ledUS-supported coalition of Gulf forces continue to fight, civilians in Yemen remain under blockade and prevented from accessing proper humanitarian assistance. In dealing with the situation, the UN Security Council (UNSC) adopted a resolution (UNSCR 2216) which authorized an arms embargo and “Reaffirm[ed], consistent with [IHL], the need for all parties to ensure the safety of civilians, including those receiving assistance[…]”. The resolution also “urge[d] all parties to facilitate the delivery of humanitarian assistance, as well as rapid, safe and unhindered access for humanitarian actors to reach people in need of humanitarian assistance, including medical assistance.’ Although the resolution recognizes that humanitarian exigencies are applicable in the Yemen conflict, it seems to signal that that the UNSC does not perceive the conduct of blockades as an illegal practice, or it does not yet have the political will to determine such illegality. In support of that view, one could refer to the fact that the UNSC has established a Sanction Committee and put forward directions to ensure compliance with its decisions concerning the arms embargo, while it did not do the same regarding the humanitarian aspects of Resolution 2216 (see, UNSCR 2140,107).

Emerging legal opinions on the legality of blockade:

Some commentators have recently extensively discussed the legality of the Israeli blockading regime. Based on these discussions, it appears that the Israeli regime makes some compelling arguments concerning the legality of blockades in relation to IHL. In that, the core argument of the Turkel Commission on the Flotilla Incident, concerning the six humanitarian vessels that were captured by the Israeli Defense Forces concluded that blockading is a legal method in international armed conflicts (IAC), but illegal in non-international armed conflict (NIAC). Having classified the situation as IAC, the Turkel Commission established that the Israeli blockade is legal. Heller has criticized the Israeli position, but he accepted the Israeli argument that Israel has the right to blockade Gaza in IAC on the basis that a blockade is legal in IAC under the law of neutrality. Kontorovich added that blockades are “entirely” legal in IAC, and that a blockade ‘necessarily puts pressure on the civilian economy and well-being’.

A few reflections:

In the author’s view, the distinction between IAC and NIAC, which is often emphasized in legal commentaries on blockades, is only useful to determine the legality of blockades from a law of neutrality standpoint and does not have bearing on the lawfulness of blockades under IHL. Furthermore, civilians can ‘never’ be the target of a military tactic such as blockade under international (humanitarian) law. Attacking civilians intentionally while aware of their civilian status is a war crime, in that, blockades which are directed at civilian population can never be lawful. At any rate, proper referencing to IHL principles and rules seems to be lacking in this conversation. Again, IHL does not (yet) make the determination regarding whether a blockade as an umbrella tactic is lawful or unlawful. Again, to establish such legality considering IHL, each concrete method which contributes to a given blockade is to be examined.

Apart from the law in the books should come to mean on this subject, there is an urging reality that must be addressed with greater emphasis. In the author’s view, contemporary blockades such as the blockade in Yemen do not only render useless the objects that are indispensable for the civilian population, but also the application of IHL itself. IHL envisages a context in which civilians and fighters, military targets and civilian objects, those who fight and those who are rendered hors de combat are to be discriminated. The effects of blockades reach everyone and everything within the besieged parameters, including the civilian population and objects, during and after the employment of blockades, resulting in inter alia the hunger, spread of diseases the demolition of water, education, health, food, transportation structures as witnessed in Yemen. Blockading about 80% of Yemen and its approximately 24 million population may certainly not be justified as discriminate under IHL under any legitimate reason. The conduct of blockading in this sense is inherently indiscriminate, thus unlawful.

Such a realization begs several fundamental questions under IHL: Does the blockade in Yemen follow the three cardinal principles of distinction, proportionality, and precautions? Would this or any contemporary blockade conform to such principles, without losing its core military objective? Can a contemporary blockade discriminate between fighters/military objects and civilians and objects? Moreover, what could potentially be the proportionate military objective that justifies the starvation, infection, slow-motion death of an entire population?

Conclusions and Recommendations:

As the situation in Yemen reveals, a blockade could amount to numerous IHL violations with few conceivable military advantages. It also reveals that the IHL framework governing blockades does not receive enough attention and thus does not provide satisfactory protections to civilian populations and objects during 21st Century armed conflict. Therefore, this blog illustrated that the legal status of the ancient naval method of blockade is ill adapted and ought to be developed in parallel to the evolution of contemporary armed conflict. As the situation in Yemen showed, the slow progress in this area of law has far reaching consequences on the lives and living of civilian populations. Therefore, this blog post thus reiterates the urgent need for a treaty process on blockades, a process which is not reliant on political will, but also the opprobrium among expert practitioners.

For the time being, it is plausible to say that there are two separate legal tests that can together determine the legality of blockades: The first examines blockade from a law of neutrality standpoint, and the second from an IHL one.For the former, the three-part test of notification, effectiveness and impartiality provides a good framework to regulate the relation between belligerents and neutrals in the context of a blockade regime. For the latter law, and for the relation between belligerents and civilians and civilian objects, every blockade regime taking place today must be examined under the core principles of IHL. Furthermore, each concrete military operation in furtherance of a blockade must be carefully examined under concrete IHL rules. As shown, the NIAC and IAC classification can only determine whether a blockade is prima facie lawful under the law of neutrality. For IHL, however, this classification only determines which specific IHL treaty-rules apply and does not have bearing on legality of the entirety of the blockade regime itself.