This was a reference for a preliminary ruling from the Tribunale amministrativo regionale per la Sicilia (Regional Administrative Court, Sicily, Italy) on the interpretation of Directive 2009/16/EC of the European Parliament and of the Council of 23 April 2009 on port State control (OJ 2009 L 131, p. 57, and corrigenda OJ 2013 L 32, p. 23, and OJ 2014 L 360, p 111), as amended by Directive (EU) 2017/2110 of the European Parliament and of the Council of 15 November 2017 (OJ 2017 L 315, p. 61) (the Directive).

The case concerned the legality of two detention orders issued by the Italian authorities with regard to the Sea Watch 3 and the Sea Watch 4, two vessels owned by Sea Watch eV, a humanitarian non-profit NGO registered in Berlin, Germany. The purpose of that NGO is the rescue of persons in danger or distress at sea, as well as the maintenance and operation of ships and aircraft for that purpose. The two vessels fly the German flag and have been certified by a classification and certification body established in Germany as 'general cargo/multipurpose' ships.

Held: The Court hereby rules:

1. The Directive must be interpreted as:

• applying to ships which, although classified and certified as cargo ships by the flag State, are in practice being systematically used by a humanitarian organisation for non-commercial activities relating to the search for and rescue of persons in danger or distress at sea; and
• precluding national legislation ensuring its transposition into domestic law from limiting its applicability only to ships which are used for commercial activities.

2. Article 11.b of the Directive must be interpreted as meaning that the port State may subject ships which systematically carry out search and rescue activities and which are located in one of its ports or in waters falling within its jurisdiction, having entered those waters and after all the operations relating to the transhipment or disembarking of persons to whom their respective masters have decided to render assistance have been completed, to an additional inspection if that State has established, on the basis of detailed legal and factual evidence, that there are serious indications capable of proving that there is a danger to health, safety, onboard working conditions, or the environment, having regard to the conditions under which those ships operate.

3. Article 13 of the Directive must be interpreted as meaning that, during more detailed inspections, the port State has the power to take account of the fact that ships which have been classified and certified as cargo ships by the flag State are, in practice, being systematically used for activities relating to the search for and rescue of persons in danger or distress at sea in the context of a control intended to assess, on the basis of detailed legal and factual evidence, whether there is a danger to persons, property or the environment, having regard to the conditions under which those ships operate. By contrast, the port State does not have the power to demand proof that those ships hold certificates other than those issued by the flag State, or that they comply with all the requirements applicable to another classification.

4. Article 19 of the Directive must be interpreted as meaning that, in the event that it is established that ships which are, in practice, being systematically used for activities relating to the search for and rescue of persons in danger or distress at sea, despite having been classified and certified as cargo ships by a Member State which is the flag State, have been operated in a manner posing a danger to persons, property, or the environment, the Member State which is the port State may not make the non-detention of those ships or the lifting of such a detention subject to the condition that those ships hold certificates appropriate to those activities and comply with all the corresponding requirements. By contrast, that State may impose predetermined corrective measures relating to safety, pollution prevention, and onboard living and working conditions, provided that those corrective measures are justified by the presence of deficiencies which are clearly hazardous to safety, health, or the environment, and which make it impossible for a ship to sail under conditions capable of ensuring safety at sea. Such corrective measures must, in addition, be suitable, necessary, and proportionate to that end. Furthermore, the adoption and implementation of those measures by the port State must be the result of sincere co-operation between that State and the flag State, having due regard to the respective powers of those two States.

The Directive must be interpreted, having regard to its objective and its content, by taking account not only of the SOLAS Convention but also of the United Nations Convention on the Law of the Sea (UNCLOS). UNCLOS was concluded by the European Union, with the result that it is binding on the EU and its provisions form an integral part of the EU legal order. Furthermore, it has primacy, within that legal order, over acts of EU secondary legislation, which means that those acts must be interpreted, as far as possible, in conformity with the provisions of that Convention (see, to that effect, judgments of 30 May 2006, Commission v Ireland, C‑459/03, EU:C:2006:345 [82]; of 3 June 2008, Intertanko, C‑308/06, EU:C:2008:312 [42], [53]; and of 11 July 2018, Bosphorus Queen Shipping, C‑15/17, EU:C:2018:557 [44] (CMI180)).

The main objective of UNCLOS is to codify and develop the rules of general international law relating to the peaceful co-operation of the international community when exploring, using, and exploiting marine areas. To that end, it determines the legal regime applicable to the various marine areas identified therein (which include the territorial sea and the high seas), establishing the substantive and territorial limits of the sovereign rights and the jurisdiction of the States in those various marine areas (Intertanko [55], [57], [58]).

That legal regime seeks to strike a fair balance between the respective and potentially conflicting interests of States as coastal States and flag States (Intertanko [58]; Bosphorus Queen Shipping [63]). That fair balance is characterised by the exclusive power which every State is recognised as having, under art 91 of UNCLOS, to fix the conditions for the grant of its nationality to ships, for the registration of ships in its territory, and for the right to fly its flag. The exercise of that power is given material expression through the act, by the flag State, of classifying and certifying the ships which fly its flag, or of having those ships classified and certified by a body authorised to do so, having verified whether those ships have complied with all the requirements laid down by the applicable international Conventions (Intertanko [59]; Rina, C‑641/18, 7 May 2020, EU:C:2020:349 [43], [44], [46] (CMI774)).

Furthermore, every State, according to art 92 of UNCLOS, has exclusive jurisdiction over ships flying its flag on the high seas. This results in a certain number of obligations for the flag State which, as can be seen from arts 94.1-94.3, include the obligation to exercise effectively its jurisdiction and control over those ships and the obligation to take all such measures as are necessary to ensure safety at sea with regard to equipment, seaworthiness, training, and labour conditions. In addition, the flag State must, under art 94.4, ensure that the master, officers and, to the extent appropriate, the crew are conversant with and observe the applicable international regulations concerning the safety of life at sea.

It follows that, on the high seas, a ship is subject to the exclusive jurisdiction of the flag State and is governed by the law of that State (judgments of 24 November 1992, Poulsen and Diva Navigation, C‑286/90, EU:C:1992:453 [22]; and of 25 February 2016, Stroumpoulis, C‑292/14, EU:C:2016:116 [59] (CMI45)), in particular as regards safety at sea and the safety of life at sea. More generally, a ship in a marine area other than the high seas remains subject, in that area, to the jurisdiction of the flag State (see, to that effect, judgment of 13 June 2018, Deutscher Naturschutzring, C‑683/16, EU:C:2018:433 [53], [54] (CMI190)), although it may be subject to controls carried out by the State having sovereignty or jurisdiction over that area, within the limits of the competences and the powers of that State.

The fair balance between the respective interests of coastal States and flag States is also characterised by the fact that the sovereignty of a coastal State extends, as can be seen from art 2.1 of UNCLOS, beyond its land territory, including its ports, and beyond its internal waters (Poulsen and Diva Navigation [28]; Stroumpoulis [59]), to the belt of sea adjacent to its territory, described as the 'territorial sea'.

The concept of 'coastal State' referred to in UNCLOS partially overlaps with that of 'port State' referred to in the Directive. The sovereignty enjoyed by a coastal State over its territorial sea is, however, to be understood as being without prejudice to the obligation placed on that State by art 24.1 of UNCLOS not to obstruct, except in accordance with that Convention, the right of foreign ships to innocent passage through its territorial sea, which should be understood under arts 17 and 18 as the right to navigate through that sea for the purpose of proceeding to the internal waters of the coastal State, calling at one of the ports of that State, or proceeding from that port, those waters, or that sea. That being the case, the coastal State has the power to adopt, under arts 21.1 and 21.4 of UNCLOS, laws and regulations relating to the innocent passage of foreign ships through its territorial sea, and in particular to the safety of navigation, with which ships making such passage must comply. In addition, in order to be considered 'innocent' that passage must have the characteristics set out in art 19 of that Convention.

In Pt VII relating to the high seas, UNCLOS lays down, in art 98.1, a 'duty to render assistance' which is derived from the customary law of the sea, pursuant to which every State must require any master of a ship flying its flag to render assistance to persons in danger or distress at sea, in so far as they can do so without serious danger to their ship, the crew or the passengers, and in so far as such action may reasonably be expected of them. In addition, art 18.2 specifies that the fact that a ship has rendered assistance to such persons may entail the passage of that ship through the territorial sea of a coastal State, including stopping and anchoring in such an area if necessary.

Accordingly, the implementation of the duty to render assistance at sea has legal consequences for the respective powers of flag States and coastal States as regards ascertaining whether the rules on safety at sea have been complied with. In that regard, it is necessary to take account, for the purpose of interpreting the provisions of the Directive, of art 4.b of the SOLAS Convention, pursuant to which persons who are on board a ship by reason of force majeure or in consequence of the obligation laid upon the master to carry shipwrecked or other persons must not be taken into account for the purpose of ascertaining the application to that ship of any provisions of that convention.

It follows that, in a situation where the master of a ship flying the flag of a State that is a party to the SOLAS Convention has implemented the duty to render assistance at sea, neither the coastal State which is also a party to that Convention nor the flag State can make use of their respective powers to ascertain whether the rules on safety at sea have been complied with in order to verify whether the presence of those persons on board may result in the ship in question infringing any of the provisions of that Convention.

The systematic use of cargo ships for activities relating to the search for and rescue of persons in danger or distress at sea may not be regarded, solely on the ground that it results in those ships transporting persons in numbers which are out of all proportion to their capacity in that regard as derived from their classification and certification, and regardless of any other circumstance, as an 'unexpected factor' for the purposes of the Directive, permitting the port State to undertake an additional inspection. Such an interpretation would be contrary to UNCLOS inasmuch as it would be such as to hamper the effective implementation of the duty to render assistance at sea laid down in art 98 of that Convention. In addition, it would not be compatible with art 4.b of the SOLAS Convention.

By contrast, the wording of the Directive does not preclude a finding, depending on the circumstances of the case, that ships which systematically carry out search and rescue activities and which are located in a port or in waters falling within the jurisdiction of a Member State after having entered those waters and after having completed all operations relating to the transhipment or disembarking of persons to whom their respective masters decided to render assistance when they were in danger or distress at sea have 'been operated in a manner posing a danger to persons, property or the environment', as the Advocate General noted in his Opinion (CMI1772). In that regard, it should be noted that, in specifying that the decision to undertake an additional inspection 'is left to the professional judgement of the competent authority', the Directive confers on the competent authority of the Member State concerned a broad discretion to determine whether those circumstances are such as to constitute an 'unexpected factor' justifying such an inspection.

However, the decision taken by that authority must nevertheless still be reasoned and, as to the substance, justified both in law and in fact. In order for this to be the case, that decision must be based on serious indications capable of establishing that there is a danger to health, safety, onboard working conditions, or the environment, in view of the relevant provisions of international and EU law, having regard to the conditions under which the operation in question took place.

It is also apparent from the Directive and the rules of international law in the light of which it must be interpreted that, before determining the corrective measures which it intends to impose, the port State must inform the flag State in writing of the circumstances and reasons which led to the inspection and the detention of a ship flying its flag, communicating to that State the report or reports drawn up following that inspection. That requirement applies regardless of the identity of the flag State and thus regardless of whether that State is another Member State or a non-Member State.

It is clear from art 94.6 of UNCLOS that a State which has clear grounds to believe that proper jurisdiction and control have not been exercised with respect to a ship may report the facts to the flag State, which must, upon receiving such a report and within the framework of its competences and powers, investigate the matter and, if appropriate, take any action necessary to remedy the situation. That provision means that the flag State is to take, with regard to ships which fly its flag, all such measures as are necessary to protect the interests of the coastal State which has made the report (see Intertanko [62]; Parliament and Commission v Council, C‑103/12 and C‑165/12, 26 November 2014, EU:C:2014:2400 [63]).

In addition, in relations between Member States, account must be taken of the principle of sincere co-operation referred to in Article 4(3) TEU, which lays down an obligation for Member States, generally and thus in connection with situations governed by the Directive, to assist each other, in full mutual respect, in carrying out tasks which flow from the Treaties, to take any appropriate measure to ensure fulfilment of the obligations resulting from, inter alia, acts of the institutions of the Union, and to refrain from any measure which could jeopardise the attainment of the Union's objectives. In view of that principle, the Member States are required to consult each other and to co-operate sincerely in the exercise of their respective powers of control, so as to ensure that the obligations under the Directive are fulfilled by the competent State while safeguarding their effectiveness. This is all the more important given that, as EU law currently stands, there are no provisions specifically governing the systematic activities relating to the search for and rescue of persons in danger or distress at sea at issue in the main proceedings.