The Legal Basis of Israel’s Naval Blockade of Gaza
Prof. Ruth Lapidoth, July 18, 2010
Jerusalem Issue Briefs Vol. 10, No. 4
-The relations between Israel and Hamas are in the nature of armed conflict.
Nowadays no formal declaration of war is needed. Hence the rules of the laws
of armed conflict apply. This means that Israel may control shipping headed
for Gaza – even when the vessels are still on the high seas.
-The rules of naval warfare have not been fully codified in a treaty and are
in the nature of binding customary rules. They can be found in the relevant
manuals of Western armies (in particular the U.S. and Britain) and in the
San Remo Manual prepared by a group of experts.
-In order to be legal, a blockade has to be declared and announced,
effective, non-discriminatory, and has to permit the passage of humanitarian
assistance to the civilian population. In addition, the San Remo Manual of
1994 includes two conditions: first, the state which applies the blockade
may decide where and when and through which port the assistance should reach
the coast. In addition, the state may require that a neutral organization on
the coast should verify who is the recipient of the assistance. In Gaza, for
instance, does it reach the civilians or Hamas?
-A ship that clearly intends to breach the blockade may be stopped already
when it is still on the high seas. Stopping the flotilla heading for Gaza in
international waters 100 kilometers from Israel was not illegal; in time of
armed conflict, ships intending to breach the blockade may be searched even
on the high seas.
-Israel is within its rights and is in full compliance with international
law because it has fulfilled all of the above-mentioned conditions for a
lawful blockade. E.g., in January 2009 Israel notified the relevant
authorities of its intention to establish a blockade of the Gaza coast.
What is the legal basis of Israel’s naval blockade of Gaza? The relations
between Israel and Hamas (which has ruled the Gaza Strip since 2007) are in
the nature of armed conflict, meaning that the rules of the laws of armed
conflict apply. This means that Israel may control shipping headed for
Gaza – even when the vessel is still on the high seas. Israel may not do so
in the territorial sea of a third country, such as Cyprus, but in time of
armed conflict Israel may check vessels on the high seas that are headed for
A naval blockade means preventing the passage (entry or exit) of all vessels
to or from the ports and coastal areas of the enemy, irrespective of the
kind of cargo carried by these vessels. One has to define clearly the
borders of the area to which the blockade applies. The blockade has to be
distinguished from other institutions of naval warfare, such as exclusion
zones and security zones.
The Sources of International Law on Blockades
What are the sources of international law on blockades? The rules on
blockades are based on customary international law, as there is no
comprehensive international treaty on this subject. Customary law is binding
in international law. According to Article 38 of the Statute of the
International Court of Justice, the sources of international law are: a)
international treaties, b) international custom, and c) general principles
of law recognized by civilized nations. A binding customary rule is created
when many states have for a long time behaved in a certain way and have done
so because they felt an obligation to behave in that manner.
Blockades have been in existence for hundreds of years. They were mentioned
specifically in the 1856 Declaration of Paris (after the Crimean War)
Respecting Maritime Law. A more detailed text followed in 1909 – the London
Declaration on Naval Warfare. This declaration sought to codify the rules of
war at sea, but the states that participated in the declaration never
ratified it. However, states actually followed the rules laid down in the
declaration, and thus its provisions became binding customary rules.
The customary rules on blockade can be found in the manuals of the laws of
war issued by certain Western countries such as the United States and
Britain. In addition, there is a manual prepared by an international group
of experts in 1994 called the San Remo Manual. (While some speak about the
San Remo Agreement, there was no agreement, but rather a manual.) In
addition, the general principles of the laws of armed conflict apply also to
When Is a Blockade Legal?
In order to be legal, several conditions have to be fulfilled. The first is
the requirement to give widespread notice when a blockade is applied and to
make sure that any ship that is stopped knows that there is a blockade.
Nowadays the problem of notification is much easier than in the past because
of the great improvement in communications.
Another condition for the legality of a sea blockade is effectiveness. It is
not enough simply to declare a blockade. It has to be enforced, otherwise it
is not valid and legal.
According to a further condition, a blockade should not cut off an unrelated
foreign state from access to the sea. In the case of Gaza, the blockade does
not prevent Egypt from reaching the sea.
Furthermore, a blockade has to be based on equality: It must apply to
everybody. Of course there is always the possibility that the blockading
party may give special permission to certain neutral ships to go through,
but these are exceptions.
A blockade has to permit the passage of humanitarian assistance if needed.
However, the San Remo Manual includes two conditions (in Article 103):
first, the blockading party may decide where and when and through which port
the assistance should reach the coast. In addition, the state may require
that a neutral organization on the coast should control the distribution of
the items. For instance, in Gaza, does it reach the civilians or Hamas?
Finally, there is the condition that a state may not starve the civilian
population (San Remo, Article 102). This conforms also to the general
principles of the laws on armed conflict.
What If a Ship Disobeys the Blockade?
What may be done to a ship that disobeys the blockade? Here, there may be a
distinction between merchant ships and warships. A merchant ship may be
visited, searched, or captured; and if the ship resists, it may be attacked.
The situation of neutral warships is not quite clear: Warships may also be
searched and captured, but opinions are divided on whether they may be
attacked. An attack is certainly permitted in a situation of self-defense.
A ship that clearly intends to breach the blockade can be dealt with while
it is still on the high seas. Stopping the flotilla in international waters
100 kilometers from Israel was legal: In time of armed conflict, ships
breaching the blockade may be searched even on the high seas.
Precedents of Blockades
There are numerous precedents of blockades. During the Korean War between
1950 and 1953 there was a blockade. In 1971, when Bangladesh tried to secede
from Pakistan, India applied a blockade. During the Iran-Iraq war between
1980 and 1988, there was a blockade of the Shatt el-Arab. Lebanon was
blockaded for several months in the 2006 war between Israel and Hizbullah,
and Israel allowed safe passage from Lebanon to Cyprus for humanitarian
In the treatment of the flotilla heading for Gaza, Israel has acted in
compliance with international law because it has fulfilled all the
conditions for a lawful blockade. In January 2009 Israel notified the
relevant authorities of its blockade of Gaza – a lawful means of naval war.
The existence of an armed conflict between Israel and Hamas in Gaza was well
known and did not need a special declaration to that effect.
But Gaza Is Not a State
Can Gaza be considered an enemy although it is not a state? According to
international law, this is possible. In any case, according to various
judgments of Israel’s Supreme Court, the conflict with Gaza is an
international conflict and not an internal one because Gaza is not part of
Israel. Neither Gaza nor the West Bank have been annexed by Israel, nor has
Israel’s “law, jurisdiction and administration” been extended thereto (as
was done with east Jerusalem in 1967 and the Golan Heights in 1981).
With regard to the status of Gaza: the territory was under Ottoman
sovereignty from 1517 until 1917, and then it became part of the British
Mandate for Palestine. In 1948 Britain left the area and Gaza was occupied
by Egypt, but Egypt never annexed it. In 1967 Gaza was occupied by Israel,
which also did not annex it. In 2005 Israel withdrew from Gaza, and in 2007
it was completely taken over by Hamas. Some say that Gaza is an area sui
generis, which means a special situation, while according to others, it is a
self-governing territory with certain powers but not with all the powers of
In both the 1993 Israeli-Palestinian Declaration of Principles on Interim
Self-Government Arrangements and the 1995 Israeli-Palestinian Interim
Agreement on the West Bank and the Gaza Strip, it was agreed that after a
certain period of time negotiations would take place on the permanent status
of Gaza and the West Bank, but these negotiations have so far failed. The
2003 Roadmap, to which both parties have agreed, foresees a two-state
solution, and that a Palestinian state should be established by agreement
Is Israel Still an Occupier?
A recurring question is whether Gaza is still occupied or not. Some say that
since Israel is still in control of Gaza’s airspace and adjacent sea, Israel
is still the occupier. According to another opinion, under the Hague
Regulations of 1907 (Respecting the Laws and Customs of War on Land),
occupation has to include full control of the area. (“Territory is
considered occupied when it is actually placed under the authority of the
hostile army. The occupation extends only to the territory where such
authority has been established and can be exercised.” – Article 42), and of
course Israel does not control the whole territory of Gaza. Therefore, it is
not responsible for what happens there.
In my opinion, since Israel is not in control of Gaza, it is not the
occupier, but in those areas in which Israel still has control – which means
sea and airspace – Israel is responsible. Here we have to distinguish
between full control of the territory and control only of the sea and
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1. Natalino Ronzitti, “Naval Warfare”, in Max Planck Encyclopedia of Public
International Law, ed. Rüdiger Wolfrum, Oxford U.P., 2008.
2. Wolf Heintschel von Heinegg, “Blockade”, in Max Planck Encyclopedia of
Public International Law, ed. Rüdiger Wolfrum, Oxford U.P., 2008.
3. Oppenheim – Lauterpacht, International Law, Vol. 2: “Disputes, War and
Neutrality”, Seventh Edition, London, Longmans 1952, pp 768-797
4. Charles Rousseau, Le droit des conflits armes, Paris, Pedone, 1983, pp
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Prof. Ruth Lapidoth, a Fellow of the Jerusalem Center for Public Affairs, is
widely recognized as a leading authority on international law. She is a
recipient of the 2006 Israel Prize in Legal Research and of the 2000
Prominent Woman in International Law Award from the American Society of
International Law. Prof. Lapidoth served in the Israeli delegation to the UN
in 1976, and in 1979 was appointed Legal Advisor to the Israel Ministry of
Foreign Affairs. She is the author of nine books and more than a hundred
articles on international law, human rights, the Arab-Israeli conflict and