Blockade, 50 Int'l L. Stud. Ser. US Naval War Col.

283,
317 (1955)

i. Establishment and Notification.

The formal requirements of a blockade concern the manner by which it
must be established and its existence made known. The authority to
establish a blockade rests solely with the belligerent government. For
this reason a declaration of blockade will generally be made direct by the
blockading state, though it may be made by the naval commander instituting
the blockade, who thereby acts on behalf of his government. In
either case the necessity for a declaration containing the date a blockade
will begin, and its geographical limits, is clear. Since knowledge of the existence of a
blockade is deemed essential to the
offenses of breach and attempted breach of blockade, it is customary that
neutral governments be notified by the blockading state of the establishment
of a blockade and that the local authorities within the blockaded
area receive similar notification from the commander of the blockading
forces.8

2. Effectiveness
Once a blockade has been properly declared and its existence made known
it must satisfy three conditions in order to be considered binding: it must
be effectively maintained, it must not bar access to neutral ports and coasts,
and finally, it must be applied impartially. Each of these customary
requirements require further elaboration.
The obvious intent of the requirement of effectiveness is to prevent
belligerent resort to so-called "paper" blockades, that is, to the practice
of declaring blockades when the naval power available is utterly inadequate
to the task of enforcement. On the other hand, a blockade is effectively
maintained when all-or nearly all-of the vessels attempting to enter or
to depart from a blockaded area are prevented from so doing by the blockading
force. Between these two situations doubt may well arise as to
whether in a concrete instance a blockade has succeeded in meeting the test
of effectiveness, and it would appear that the most satisfactory formula is
that the degree of effectiveness required must be such as to render ingress
to or egress from the blockaded area dangerous-hence seizure for breach
of blockade probable. 10

It is implicit in the customary rule of effectiveness, but should be given

special emphasis in view of more recent developments, 1 that the means a
belligerent may use in maintaining a blockade are not unlimited. More
specifically, the effectiveness required of valid blockades cannot be secured
by means violative of other firmly established rules. The element of danger
associated with an effective blockade is therefore to be understood in terms
of a liability to seizure and eventual condemnation, though not in terms
of a liability to destruction upon entrance into the forbidden area.1 But
there is nothing in the traditional law preventing the use either of submarines
or of aircraft in maintaining a naval blockade, so long as their
employment does not thereby result in a violation of the rules applicable
to surface vessels. S
3. Application of Blockade
The third substantive principle governing the operation of a blockade is
that it must be applied impartially to the vessels of all states-including
the vessels of the blockading belligerent.' The purpose of this rule is to
prevent a blockading belligerent from taking advantage of his position
in order to discriminate in the treatment accorded to different countries.
Thus a belligerent would violate the principle of impartiality if he allowed
the vessels of certain states to pass through the blockaded area while
excluding the vessels of other states. However, impartiality in the treatment
of the vessels of all states refers only to the standard of behavior
demanded of the blockading belligerent within the area that is being
blockaded. More precisely, the rule applies only with respect. to the
vessels of all states attempting either to enter or to depart from the blockaded
ports or coast by sea. 9 There is no requirement that a blockade
must bear with equal severity upon the trade of neutral states.

ERIC ENGLE

B. PRECONDITIONS TO LAWFUL PEACEABLE BLOCKADES

Blockades must be real,29 effective, 30 and neither mere
paper blockades nor pretexts. 31 These requirements are to
prevent predatory fake blockades intended only as an excuse
for privateering. The blockade must be announced publically,
meaning that other states must have notice of it.32

Pacific blockades may be used as a reprisal, a

form of intervention, or a form of suppression of human rights
abuses.3 4

a. Article 42 of the U.N. Charter

Is the use of a pacific blockade a violation of the prohibition
of the use of force outlined in Article 42 of the U.N. Charter so
that U.N.S.C. approval is required for the imposition of a
pacific blockade? This article answers that question in the
negative. U.N.S.C. authorization is not required for a state to
undertake a pacific blockade because peaceful blockage is not
an act of war. 65 In fact, it is an act intended to avert war.

The right of any state to enforce

international law is especially evident where the state exercises
its sovereign power to remedy and deter violations of jus
cogens. The use of pacific
blockades to prevent such gross violations of universal human
rights is therefore justified as a necessary and proportional
countermeasure short of war to enforce jus cogens as a form of
defense of the Syrian people from their own government.
A pacific blockade is as a measure short of war. 96 It is an
exercise of police power, but it does not use force and therefore
does not require U.N.S.C. approval. 97 States may justifiably
invoke their customary international right to undertake a
pacific blockade to enforce non-derogable peremptory rules of
international law: jus cogens.98

D. EVEN IF A PACIFIC BLOCKADE OF SYRIA WERE ILLEGAL,

IT WOULD BE JUSTIFIED BY THE DOCTRINE OF NECESSITY
Even if imposing a pacific blockade was a violation of the
prohibition of the use of force, the defense of justification would
apply. One justification for the use of force is self-defense89 or
the defense of others. 90 Another is necessity. 9 1 Yet another is
the enforcement of jus cogens norms. 92 Recall that jus cogens
norms are universal rules which may be enforced by any
state.93

FRAUNCES

1. Initial notice is still given through formal diplomatic channels to all states, but greater
specificity is required to make the zone's boundaries clear to neutral vessels since surface
ships no longer demarcate them.'?6 Blockaders are also expected to state generally the
intended method of blockade enforcement.l07Under the new principles, the method of
enforcement is critical to a determination of the proper size of the blockade and, therefore,
to its lawfulness.

2. The Principle of Reasonableness The principle of reasonableness requires states to

conduct blockades of reasonable size. State decision makers determine reasonable size for
each conflict by examining the nine decision making factors. Theoretically, by considering
each of these factors in formulating their blockade, decision makers will come up with a
reasonably sized blockade that maintains an acceptable balance between belligerent and
neutral interests. While valuable as theory, the process alone tells decisionmakers little
about the appropriate size of a blockade for a given set of circumstances. Examining these
nine decisionmaking factors

The traditional law also required impartiality, which imposed a duty to apply the blockade to
all vessels regardless of nationality.29 This requirement stemmed from the Continental
response to the onerous British practice in the eighteenth and early nineteenth centuries of
barring vessels from certain ports while allowing British commercial interests to continue
trading there.30 The principle of impartiality, eventually accepted by the British, made such
commercial blockades unlawful. Unlike the first four principles, the requirement to respect
neutral rights represented a more complex trade off between neutral and belligerent rights
and duties. Generally, the blockading force had the right to prevent all neutral directly with
the blockaded port or coast. In return for respecting that right, neutrals retained the right to
trade with other neutral countries. As a result, blockading forces could not extend their
blockade to block access to neutral ports.31
WYLIE
It is agreed then that blockades must be effective, but Criterion of
there is no agreement to define 'effectiveness' ; a fact which 'Effectiveis
recognised by Article 3 of the Declaration of London :- ness.'
'The question whether a blockade is effective is a question
offact.'
Each case can only be decided on its own circumstances, British and
first by the national tribunal and then by the International American
Court of Appeal. In England 3 and in America 4 the prin- View.
ciple applied in the past has been that a blockade is sufficiently
effective provided that, under normal conditions, a breach of it would be unlikely to succeed,
or at least very
difficult.

It was laid down by the Declaration of Paris that Blockade

blockades to be valid must be effective, that is to say, must be
maintained by a force sufficient really to prevent access to Effective.
the coast of the enemy. upported by the material strength to make them effective
Effective. on the spot, have been by universal agreement for a long
time inadmissible.

It is agreed then that blockades must be effective, but Criterion of

there is no agreement to define 'effectiveness' ; a fact which 'Effectiveis
recognised by Article 3 of the Declaration of London :- ness.'
'The question whether a blockade is effective is a question
offact.'
Each case can only be decided on its own circumstances, British and
first by the national tribunal and then by the International American
Court of Appeal. In England 3 and in America 4 the prin- View.
ciple applied in the past has been that a blockade is sufficiently
effective provided that, under normal conditions, a breach of it would be unlikely to succeed,
or at least very
difficult.

A distinction must be made in the first place between

'declaration' and 'notification.' In the words of the Report
of the Drafting Committee: 'The Declaration of blockade
is the act of the competent authority (a Government or
commander of a squadron), stating that a blockade is, or is
about to be established under conditions to be specified.
The notification is the fact of bringing the declaration of
blockade to the knowledge of the neutral powers or of
certain authorities': or, it should be added, of the individual
neutral vessel in certain circumstances, as will be seen later.
This distinction is clearly drawn in Article 8 of the
Declaration of London :-
'A blockade, in order to be binding, must be declared in
accordance with Article 9, and notified in accordance
witlh Articles i i and I6.'

As to the necessity for a declaration, and as to its requirements,

there can hardly be dispute. A blockade is an
act of sovereignty I and can only be imposed by a Government
or a naval officer with the authority of his Government:
but such authority will be presumed, if the circumstances are
such that express instructions are impossible. In other
words, a blockade is an act of sovereignty which may be
delegated.' But approval and adoption by the Government
is necessary: such adoption relating back to the
date of the imposition of the blockade.3

JEG MONTMORENCY

Blockade was, and is, a police measure against nonbelligerents

who for their own monetary profit decide to interfere
in the war. It was and is a penal doctrine.