Crossing Borders in International Air and Space Law

Prof. Pablo Mendes De Leon discusses principal aspects of international air and space law. It draws parallels between the two fields of law, namely, air and space law, while marking the differences. Both fields of law are part of international law. This affiliation, coupled with the occurrence of topical developments in air transport and space activities, invites to examining interesting multilevel jurisdictional questions, in which various layers and fields of law interact. According to him, if we want to contribute to the realisation of the ultimate purpose, namely, the healthy and balanced development of a global aviation and space industry, we must be prepared to cross borders including the borders of our own field of interest – be it air law, space law, other fields of law, or the conduct of a specific policy. All these fields and interests should be prepared to learn from each other, in an interdisciplinary fashion, so as to achieve a fruitful osmosis of all those directions. The author was delighted to present this article to the Editorial Board of the India Law Journal at a time when preparations were being made for the organisation of the first international air law moot court ever. This event was jointly organised by the distinguished Sarin Memorial Legal Aid Foundation, established in India, and the International Institute of Air and Space Law of Leiden University, The Netherlands, and took place from 1 to 6 March 2010 in New Delhi.



Crossing borders is the central theme of this contribution to the India Law Journal. This term (crossing borders) will be principally applied in a legal sense to the development of air and space law, and aviation and space activities.

Both activities started with a contest. Approximately a century ago, aviation pioneers were challenged to fly an aeroplane. Exactly one hundred years ago Monsieur Blériot crossed the Chanel. In 2004, Virgin Galactic won a competition to be the first to launch a new commercial space activity, namely space tourism. Suborbital space tourism will most probably take off early 2011, with a journey to the edge of outer space for tourists. Hence, both aviation and space related activities started and perhaps can only start by challenging the human mind to move boundaries, including intellectual boundaries.

Academic attention for this subject matter at Leiden University commenced as early as 1938, when Professor Daniel Goedhuis was appointed to teach air law. A professorial chair was created in 1947 with an extension to space law in 1961, the first one of its kind in the world. This happened four years after the launching of the first satellite into outer space, that is, the Sputnik 1 operated by the then USSR. Interest in space-related sciences in Leiden enjoys a long tradition. In 1633, Leiden University established an observatory, the Sterrewacht (Star observatory) Leiden, which is the oldest still operating university observatory in the world.

Air law became the more predominant field of attention when Professor Wassenbergh signalled in 1978 the start of a liberalisation process in air transport in the US, which was followed in Europe. In 1997, Professor Haanappel discussed the question whether air and space law were autonomous fields of law, a question that, incidentally, was also alluded to by Professor Goedhuis. This question merits some attention in the present era.

II. Defining the borders of air and space law

This introduction may also serve as a clarification of the question what air and space law comprise. Many people are not so familiar with these branches of law, and may consider them “esoteric”, “extravagant” or “ethereal”. This is also to explain that there are a lot of concrete applications and implementations of these regimes. That is increasingly true for space law and has been especially true for air law since a number of decades.

Air law is connected with a myriad of areas of law, such as civil law and private international air law in the context of the liability of the air carrier for damage sustained in the course of carriage by air; criminal law, which found its way into air law upon the occurrence of hijacking and other criminal acts committed on board aircraft; the law pertaining to the financing of aircraft, and also space craft, and related assets; tax law; competition law in the context of airline alliances; European Community law and environmental law. I will discuss the latter two areas in somewhat greater detail in the course of this article.

Space law is differently organised as compared with air law. It is basically a branch of public international law. It borrows concepts from maritime law. Increasingly so space law also involves other branches of law. For instance, on the International Space Station, the criminal law of the state of the nationality of the offender applies. As regards inventions made on board the International Space Station, an activity occurring on a flight module shall be deemed to have occurred in the territory of the State of registry of the module.

A thread running through this contribution concerns securing the rule of law in a multilevel jurisdiction while crossing borders – not only physical and geographical but also non-physical borders. Multilevel jurisdiction refers to the various levels of jurisdiction to which economic and other activities are subjected. Those levels are especially present in the European Community where national law, European Community law and public and private international law increasingly interact.

To begin with reference is made to similarities and differences between air and space law, a subject which was meticulously analysed by Professor Direderiks-Verschoor. After that a case study involving European Community law and environmental law, and their interaction with public international law in the context of extra-territoriality will be concisely examined.

III. The impact of security on the development of air and space law

III.1 Similarities: The impact of security on air and space law

Conceptually, air and space law are different as the former rests on the principle of sovereignty of a state in its national airspace, whereas space law forbids claims pertaining to sovereignty in outer space as outer space has to be regarded as “the province of all mankind”. However, these conceptual differences depart from a principal concern shared by the drafters of air and space law which is security. Typically, security is a concern for which a state is responsible – so that the role of states in both air and space law is a predominant one.

Also, the medium in which aviation and space activities are carried out is a vulnerable one, as airspace and outer space are transparent. In the absence of physical boundaries such as mountains, rivers or seas in airspace, aircraft flies from one airspace into another. Also, aircraft can be used as weapons in, for instance, a terrorist attack or in a war as demonstrated by the 9/11 tragedies.

As a corollary of the transparency of airspace and outer space, there is no physical separation between national airspace and outer space. Aviation and space lawyers believe that outer space starts at about one hundred kilometres above the earth, that is, where national airspace stops. However, there is no internationally agreed border line between the two media. In the light of the development of future commercial space activities it may become necessary to determine that distinction so that operators know whether rules of air law or of space law will apply to them.

In outer space, satellites are used for military purposes, for instance, as detectors of installations on the ground. This aspect of the medium airspace and outer space accounts for the relevance of security, and of national policy interests, in the development of international air and space law.

III. 2 The impact of security on the formation of space law

In space law, security has been taken care of in a manner which is different from the approach taken in air law: not by closing access to outer space or by making it subject to permission for entry by, for instance, the community of states assembled in the United Nations. Space law lays down express prohibitions regarding the use of outer space in various multilateral space and other international treaties.

Current space law consists of five United Nations (UN) treaties, UN resolutions, related treaties such as the Anti-Ballistic Missile Treaty and the Nuclear Ban Treaty, national legislations implementing provisions of those space treaties, and that is about it.

There are no specific international rules regulating the commercial use of outer space. Liability for activities carried out in outer space and for journeys from and to outer space is regulated in a rudimentary fashion only, and only provides for state liability.

Outer space should not become a military test field let alone a battlefield. That is what the principal Outer Space Treaty of 1967 proclaims: as opposed to national airspace, there shall be free access to all celestial bodies for exploration and use by all States. Access is made subject to a number of principles that pertain to the peaceful purposes of such use and the prohibition of carrying out specified military activities and tests in outer space or on celestial bodies.

Access is also subject to the provision that the use and exploration shall be carried out for the benefit and in the interest of all countries. Outer space is deemed to be “the province of all mankind”.

Exploitation of natural, including mineral resources is another, and more sensitive matter. The argument was made that private companies should enjoy freedom of exploitation of the resources of the moon, such as the mineral gas Helium-3, in order to help us remedy our energy problems on earth. However, this is not an easy undertaking. The current regime regulating the sharing of benefits and promoting the concept of the common heritage of mankind laid down in the aforementioned Moon Agreement does not provide the legal certainty for commercial parties to begin operations.

In short, outer space, as a terra communis, is subject to international law, including international space law. We witness the long arm of terrestrial space law reaching into the more remote extra terrestrial spheres.

III. 3 Security in air law

In air law, security has been taken care of by closing national airspace for the operation of scheduled international air services foreign operators. A foreign operator may only enter the national airspace of another state if it has permission to do so. Failing to have such permission may result in military aircraft leaving a military airport on the territory of the state whose airspace is concerned and escorting the operator of the concerned foreign aircraft you through that airspace. If necessary, the foreign operator may be forced to land at an airport indicated by those air forces. As odd as it may seem, this happens nonetheless two to three times per year in for instance Dutch airspace.

The operation of state aircraft in foreign airspace is also subject to explicit permission of the state into whose airspace the foreign state aircraft is flown. Non-scheduled air transport developed on the basis of unilateral regulations after the Second World War.

Hence it is not coincidental that the two principal aviation conventions, to wit the Paris Convention and the Chicago Convention, were both drawn up at the end of a major world war: that is, in 1919 and 1944, respectively. Both agreements had a military background. The Chicago Convention can be regarded as the constitution of post World War II international civil aviation, as it contains basic principles for the safe operation of international air services and is adhered to by 191 states – practically all states.

In the absence of physical boundaries such as mountains, rivers or seas in airspace, this Chicago Convention hermetically closes national airspace by creating legal boundaries between states, which can only be opened up by international agreement, again between states. That is one of the principal reasons for making air law a special branch of law, as states have a public interest with respect to the air transport system coming under their jurisdiction and supervision.

The events which occurred on 9/11, 2001 in the World Trade Centre in New York demonstrated how states, in particular the United States, react when their vital security interests are affected by the vulnerability of airspace, as a consequence of its transparency. Rules of law, including air law on the liability of the airline, are “overruled” by the interest of preserving national security. Upon 9/11 the US government decided to close its airspace for three days for reasons of national security.

III. 4 From military security to economic security, and to protectionism?

Apart from the security interests from a military and political perspective, both airspace and outer space yield economic interests for their users, be it in different ways. These interests have profoundly affected the establishment of air and space law, and, again especially so, the formation of air law. These interests can in a way also be related to security as the existence of a national air transport system affects the vital economic interests of a state, as evidenced by the aforementioned 9/11 events.

Also, new states or newly independent states in this world do three things to begin with: they design a flag, they compose a national anthem and they set up a national airline carrying their flag. But apart from this symbolical value which states attach to air transport, states also want to keep national control of their air transport system, that is, their airlines, airports and air services operated from and into their territory.

Air traffic management is yet another field in which sovereignty and the protection of national interests appear to prevent states from implementing a more unified airspace. Since 2004, the establishment of the Single European Sky regime of the European Community, the European organisation for the safety of air traffic management, Eurocontrol, and the European Commission are working together to harmonise the European airspace for air traffic management as this would help to achieve a level playing field for operators and produce enormous environmental benefits.

If air transport is vital for a state, its economy and well-being, it is also susceptive for external influences. The air transport industry and air traffic management are affected by state interests, political power plays, climate changes, epidemics, economic ups and downs, military interests and sometimes wars, as well as influences from other fields of law and policy. Aviation has all the more been affected by a decrease in traffic demand and an increase of the price of kerosene.

Thus, aviation is a vulnerable industry; perhaps even more so than the space industry, although both operate in a three-dimensional environment. This makes them also susceptible to forces exercised in and by that environment. In short, aviation is walking through an international political and economic battlefield and a legal minefield.

This state of affairs is aggravated by the current unprecedented economic and financial conditions, exercising their cathartic forces on the economic system. Those forces focus on vital, that is, national economic interests by re-organising the economic system – and may eventually contribute to the necessary restructuring. Hence we have to ask ourselves what can be kept, what can be improved and what should be thrown away?

Some claim that as a corollary of the need to preserve national interests sovereignty is back on the agenda; that we have to rely on protectionism in order to cope with the crisis; that we are experiencing a revival of bilateralism; and that perhaps even, capacity and pricing should be re-regulated.

This economic down turn once again and perhaps more than ever shows that aviation, more than other industries, is performed Formatted in the shadow of the future. What tomorrow will look like is never sure – as those forces can arise at any unexpected moment.

At this point in time, flexibility and inventive solutions are called for. New rules may be helpful but can also exacerbate the situation. Where possible, a common approach, based on cooperation and a shared vision is called for. As regards Europe, the EC Commission can play a catalyst role in this process, and should do so in an active way.

Even if this may appear premature or anachronistic, one should look beyond the crisis and even beyond Open Skies. This article is not only intended to examine yesterday, or today, but also to cross borders by looking into the future.

Before getting there some historical milestones in the history of aviation and aviation law are marked. Special attention will be paid to the impact of liberalisation and European Community law on the course of that history, so as to contextualise the theme of the second part of this article.

IV. The impact of liberalisation on the development of aviation law

Since its early start in the period between 1910 and 1920, aviation law was neatly organised along the lines of the two major worldwide air transport agreements, namely, the aforementioned Paris Convention of 1919 and the Chicago Convention of 1944 in combination with bilateral agreements providing access to foreign airspace for the operation of international scheduled air services. So far so good, air law could be regarded as part of public international law. Vital national economic interests were best safeguarded by this system.

Today the protection of vital national security and of national economic interests is fading away in a world of liberalisation, privatisation and globalisation. Nevertheless, the major part of the aviation sector, that is, the part including the operation of air services, is the only sector which is not subject to the regime of the World Trade Organisation and the GATS. This is likely to remain so for the years to come.

In the course of the 1970s, the US introduced the deregulation process upon which the then European Economic Community followed suit. It started its own phased cross-border liberalisation process. That movement forced states to open their air transport markets – and to forget about national, vital economic interests. This was so far a unique venture which was completed in 1997, the moment on which all intra-Community services were made available to Community air carriers. Perhaps unsurprisingly, international air law and European Community (henceforth: EC) law did not form a natural bond.

Whereas international air law proceeds from adherence to sovereignty and state supervision of air transport, not only for safety and security but also for economic matters such as market access and pricing, the EC proclaims the market approach: from internal market via the common market to an open market. This market approach is also governed by principles regarding the protection of passengers and other consumers, and the environment. Frictions between European Community law and international law will not only arise and have not only arisen in the area of economic regulation but also of consumer and environmental protection.

The forthcoming discussion of the very topical issue regarding the establishment of an Emissions Tradeing System (ETS) will hopefully demonstrate the following points:

Firstly, international air law and Community law cannot always easily be matched as the former proceeds from a state-governed management of aviation relations, whereas the latter is built on a more market-oriented approach.

Secondly, policy and law are intrinsically related. My predecessor Professor Daniel Goedhuis referred in 1953 to the intrinsic relationship between politics, policy and law in international civil aviation. Also, Professor Wassenbergh referred on multiple occasions to the cohesion between law and policy in relation to the conduct of international aviation relations.

Thirdly, global problems require global solutions. This applies especially to aviation which is after all not only a cross-border but also a global undertaking.

Fourthly, the promotion of domestic policy objectives, for instance, the protection of the environment, by the extra-territorial application and enforcement of local laws can fill up jurisdictional gaps and can contribute, just as treaties, to the gradual development of international law. The extra-territorial application of domestic laws is not necessarily prohibited by international law. Some states and jurisdictions including the European Community rely on the so called “effects doctrine” as a justification of the extension of their domestic laws outside their geographical boundaries. Such a procedure is liable to create frictions with other states or persons falling under their jurisdiction who are affected by such an extension. Those frictions have to be solved, but how? –

Those questions will be examined in the following sections, to begin with the last mentioned point pertaining to extra-territoriality.

V. Extra-territoriality

V.1 Generally

Extra-territoriality in the field of air law is a bit particular because an aircraft is sometimes and for specific purposes regarded as part of the territory of the state in which the aircraft is registered. If that premise – that the aircraft is part of the territory of its registration state – is agreed upon in an international convention, there is nothing wrong with the application of domestic law on the aircraft, even if it is flying abroad.

For instance, gambling on aircraft may be regulated by the state in which the aircraft is registered. However, when the United States passed a law prohibiting gambling on all flights from and to the US, including flights operated by non-US carriers, strong protests were raised by foreign governments. They objected to the extra-terrestrial action which appeared primarily intended to protect US carriers from the competitive impact of prohibiting gambling on US carriers while permitting it on foreign aircraft.

There are many more examples of extra-territorial applications and enforcement of national laws. Such examples can be found in the field of crimes committed on board aircraft, the EC protection rules on denied boarding and delay, blacklisting of the EC-based safety measures designed to protect travellers but with extra-territorial effects, security versus passenger protection, and the disagreement between, again, the US and EC policymakers when the US wished to impose security measures at European airports infringing European rules on human rights.

In light of the topicality of the subject, that is, the Copenhagen Climate Change Conference of (7-18) December 2009, special attention is given to one example, namely the extra-territorial application of the recent EC measures on the establishment of an Emission Trade System for aviation.

V.2 The extra territorial reach of the EC based ETS

The starting point of a discussion on the subject of climate change through the establishment of an Emission Trade Scheme – henceforth referred to as: ETS - can be found in the Kyoto Protocol of 1997 which is attached to the United Nations Framework Convention on Climate Change (UNFCCC), designed to stabilise greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.

The reduction of greenhouse gasses coming from the aviation sector must be secured through the International Civil Aviation Organization henceforth referred to as: ICAO. Thus, ICAO is mandated to set up a system designed to limit or reduce greenhouse gasses emitted by aircraft, whose operators become the liable parties.

Meanwhile, the EU Emission Trading Scheme is the largest multi-national Greenhouse Gas – henceforth referred to as: GHG - cap and trade scheme. The EC ETS scheme is designed to operate as an activity under the Kyoto Protocol and the UNFCC.

As from 1 January 2012, all flights arriving at or departing from an airport located in an EC state are included with the scope of the amended ETS Directive. In other words, an Air India or Jet Airways service operated between Delhi and London or Paris is as much subject to this EC regime for the performance of its entire flight, including the passage through the airspace of other, non-EC states such as Iran and Turkey, as Easyjet operating a flight from Rome to Paris.

Hence, the EC intends to apply a scheme not only to its own operators but also to foreign operators, and not only in the airspace of its Member States but also outside, that is, in the airspace of third states and above the high seas. This wide scope calls for a discussion of international law considerations so as to secure the rule of law in a fascinating multi-level jurisdictional question.

In light of the policy measures and resolutions adopted by ICAO, the EC’s moves in the area of ETS have met with resistance. Third states argue that the EC ETS measures affect the level playing field between the aircraft operators, as EC airlines may benefit form the system, whereas the argument has also been made that the EC ETS legal framework infringes international law, in particular provisions of the Chicago Convention, ICAO resolutions and bilateral air services agreements providing for the maintenance of a level playing field between the concerned states.

So far, a cascade of arguments has been, and, admittedly, can be raised in order to point out that the EC ETS scheme infringes international law. Important aviation states and trading partners of the EC and its Member States have raised criticism against these proposed measures which they consider to be unilateral actions infringing international law. It remains to be seen whether the ETS Directive, when it will be applied and enforced in 2012, will stay unchallenged.

Even a concise analysis of the arguments would not do justice to the complexity of the problem, involving EC law, principles and policy measures, international law, such as international environmental and aviation law provisions, and international relations, including international trade relations. Also, the international playing field is affected, whereas European hubs may be by-passed by flying through for instance Istanbul and Zurich airport. However, the pertinent question is: how to proceed from here?

V.3 How to secure the law in this multiple jurisdictional question?

In solving this phenomenon outside the policy arena and inside the legal forum, as one ideally should, the choice of jurisdiction is essential, as evidenced by the case of the compatibility of the EC Regulation on Denied Boarding with international law. The European Court of Justice, it seems, prefers to check international law against European law rather than the other way around.

The choice of the most appropriate forum thus becomes essential. Yet again, law and policy go hand in hand as there is and will always be a choice for a regime determining the case in question.

Third states can choose to submit this piece of legislation to the ICAO Council suing the 27 EC states. There is historical evidence for this course of action.

In 2000, the US challenged an EC regulation which was designed to ban the operation of hushkitted (somewhat noisier) aircraft into and from EC airports. The US claimed that the noise level of the hushkitted aircraft, operated by US airlines, exceeded those of Annex 16 of ICAO, laying down Standards on environmental protection (noise and emissions). The EC regulation appeared to have one single objective, namely, to benefit EC air carriers and aircraft manufacturers at the expense of their U.S. counterparts. The U.S. sued the (then) 15 EC states as it has no treaty relations with the EC as such under the Chicago Convention. After some discussions and negotiations back and forth between the two parties, and with the interventions made by the President of ICAO, the EC withdrew its contested so-called ‘Hushkits’ regulation and replaced it by a ‘milder’ but perhaps also ‘noisier’ regulation so as to secure the rule of international law.

Third states can also rely on the Dispute settlement provisions laid down in bilateral air agreements which are in place between them and the relevant EC states. For instance, the US may wish to rely on remedies provided by the recently concluded transatlantic agreement between the EC and the US on air transport.

Finally, thought could be given to involving the International Court of Justice. However, this court does not seem to be the first instance of recourse as other remedies are still available.

ICAO may also consider asking the International Court of Justice for an advisory opinion on the validity of the EC Regulation on ETS in the light of international law. This would be unique in the history of international air law.

In conclusion, the saying made by Mark Twain “History does not repeat itself but it often rhymes” – or the French saying “L’histoire se répète” - may yet again prove its validity. The next question is how to cope with laws crossing borders without underlying international agreement for such passage.

V.4 How to cope with extra-territoriality?

Another and perhaps the more elegant solution would be to reach agreement on the subject matter. However, securing the rule of law by establishing a multilateral agreement in a multi-level jurisdiction that is dominated by international policy and commercial interests is not an easy task.

As an interim solution, comity and application of the jurisdictional rule of reason could be thought of, meaning that states should not unilaterally apply their regulations outside their boundaries, especially if this is contrary to international law. Comity should be observed in the context of the ETS. It should be seen as an ad hoc and temporary tool designed to foster regulatory convergence, harmonisation or unification, eventually resulting in a multilateral agreement.

The conclusion of a multilateral agreement is probably more effective in the long term but less realistic in the short term. However, the urgency of a global solution, fostered by the ICAO, may be dictated by the current dire economic circumstances.

Multilateral agreements are needed in the global aviation industry. They contribute to the necessary levelling of the playing field on which operators are working and flying.

This argument is demonstrated by a few recent multilateral agreements in the field of private air law, including the Montreal Agreement of 1999 on air carrier liability and the Cape Town Convention and attached agreements of 2001 on the financing of air and space craft. This said, one should not always go for the global solution, not even in aviation. Indeed, it may be questioned whether the recent coming into being of two other international private air agreements was needed in order to create a level playing field among operators of aircraft for the subject matter in question.

Reference is made to ICAO’s Convention on Compensation for Damage Caused by Aircraft to Third parties, and the Convention on Compensation for Damage to Third Parties, Resulting from Acts of Unlawful Interference Involving Aircraft, established at a diplomatic Conference which took place at ICAO’s Head Quarters April-May 2009. The texts for these conventions were drawn up following the aforementioned 9/11 events. Are multilateral agreements needed here, or could those issues also or even better be dealt with under local civil law?

Unfortunately, recalling the dramatic Amsterdam-Bijlmer crash of 1992 and the Turkish airlines crash of 2009, The Netherlands has some experience with such cases. It would seem that those and experiences in other states as well as the fact that the Rome Convention on Damage Caused by Foreign Aircraft to Third Parties on the Surface of 1952 has remained a dead letter, as it has never been applied or enforced in practice, show that national law is very well equipped to deal with those aviation related accidents.

I conclude that we may want to apply a principle which could be termed as “reversed subsidiarity”. For the reasons set out above, aviation, and space matters should in principle be regulated by multilateral agreement, unless a case can be made for the application of local law instead of international law.

At the same time it should be acknowledged that a local or regional arrangement made by, for instance, the EC can play a catalyst role in the process of drawing up an international agreement. It can for the time being in the pre-Copenhagen phase be hoped that this will apply to the EC-based ETS measures. Meanwhile, comity and respect for a balanced conduct of international relations must accompany this avenue.

VI. The future of space law

Departing from air law and national airspace, even more borders are crossed. Beyond airspace there is outer space. Beyond extra-territoriality there is the extra-terrestrial application of the laws enacted on earth.

I believe that there is a fascinating future for space law as we find ourselves on the threshold of a new era, with new technological discoveries ahead of us. As noted above, every successful scientific discovery triggers new ideas on the interpretation and application of the traditional legal concepts including the concept of the Common Heritage of Mankind.

For instance, we see the era of space tourism emerging. Next year, undertakings such as Virgin Galactic are offering trips to the edge of outer space. Suborbital flights are parabolic flights made during approximately three hours to points which are located at a distance of about hundred kilometres from the earth’s surface, that is, the edge of outer space, whereas orbital flights may go far beyond that distance. The appeal of a sub-orbital trip is that you can see from the edge of outer space the curb of the earth, enjoy the breathtaking darkness of the surroundings and experience weightlessness.

Applicants have to undergo a number of physical and psychological tests. They also have to pay 200,000 € for their ticket, and they have to sign a declaration that they will not hold the operator of the spacecraft, that is, Virgin Galactic, liable for compensation of damages and losses which they might incur during their space trip. Obviously, it can be asked whether those declarations can be upheld in court. And additional questions then arise: which courts are competent to hear cases – should they emerge - and which law is applicable?

General private international law may give some answers to these questions but at a certain point in time, when space tourism becomes a popular activity, one may need special agreements to address these questions – as the operation of space craft is very much an international, and very complex undertaking, with a number of states, private parties and international organisations such as the European Space Agency (ESA) participating in it.

A system of passenger liability of space-craft operators may be called for. Also, the boundary between air space and outer space should be further examined.

Other questions for future research and teaching concern the protection of space activities against space debris, space traffic management, the registration of space objects in national registers, the establishment of national agencies overseeing licensing and safety of such craft, and the weaponisation of outer space.

The corpus iuris spatialis has so far been succinct. This will change when private enterprises will start to carry out activities in space that go beyond exploration, such as exploitation of resources and tourism. Then, space law will be increasingly affected by a myriad of other branches of law.

VII. Concluding remarks

Aviation and space related activities are special. They are carried out in a three dimensional, transparent and continuous medium. That characterises them, and distinguishes them from other economic and operational activities. That characteristic makes them also vulnerable for influences from external forces which are exercised at sometimes foreseeable and at other times unpredictable moments. Hence, those activities are performed in the shadow of the future.

Aviation and space activities are by their very nature international, global and extra terrestrial activities. That also makes them special. Those external forces are not only of a physical nature. A myriad of branches of law and policies influence the development of international and national air and space law.

In order to create at least some legal certainty for the operators carrying out their activities in a vulnerable and multinational environment, the establishment of international agreement is indicated, and should indeed be encouraged. However, it may not always be easy or even extremely difficult to draw up multilateral agreements as domestic concerns about for instance protection of the environment or consumers stimulate the conduct of domestic or regional policy initiatives. They are, in turn, inspired by political motives.

This said, the final goal for the healthy development of a global aviation and space industry must be a worldwide solution for the subject in question. From this perspective, local policy solutions and economic downturns are the shadows of today; the global agreement paving the way for a world wide level playing field represents a vision of tomorrow, which I hope is not just an academic vision.

PROF. PABLO MENDES DE LEON is the Director of the International Institute of Air and Space Law of Leiden University, Leiden/the Hague, The Netherlands.