The “Inverted Border”: When did the Border become an Obligation to Keep In Rather than a Prerogative to Keep Out?

[Frédéric Mégret is the Hans & Tamar Oppenheimer Chair in Public International Law at the Faculty of Law, McGill University and the James S. Carpentier Visiting Professor at Columbia Law School]

The question of how Mexico and Canada police their borders has emerged as a considerable symbolic stake in the current crisis with the US. The US President has made a number of inconsistent but emphatic demands upon both states that they better police their borders. Although both Mexico and Canada have found the attitude hostile and bordering on the arbitrary, they have also committed to do more to stem fentanyl flows and illegal migrants. But on what authority can a state demand of another that it police the former’s borders from within as it were? On what basis can the border become “inverted” as it were, spelling out an obligation to keep certain things in rather than a prerogative to keep them out?

To be clear, I am not interested here in the extent to which such flows are, in fact, as much of a problem as they are presented to be (there are many arguments at least as regards Canada that the flows are infinitesimal, and as regards both Canada and Mexico that imports of fentanyl are in significant part the result of massive demand in the US), or the extent to which either Mexico or Canada have, in fact, responded successfully to these demands. What I am interested in as a much more elemental and foundational point that seems lost in the chaos of the moment and speaks to a broader reality in international law. What is striking is the ease with which it has seemingly been at least tacitly accepted by both Canada and Mexico that they do have some kind of inchoate obligation to police their borders in the way demanded by the US, so keen are they to be seen to be responding to the charge that they have been derelict. This is often outside the US making any clear case about what international obligation is being violated and outside any significant pushback on the legal foundation of such demands.

In this post, I want to reflect on how quickly assumptions can be upended in the rush to placate a hegemonic and imperious neighbor, and how we should not lose sight of a sort of international law “bottom line” in such matters. That bottom line is that, outside voluntary and presumably jointly welcome obligations, there is no a priori no general obligation to police another state’s border and that the increasing trend to demand exactly that is part of a worrying revisionist attempt at undermining some core principles of international law.

To be sure, the border is a complex construct that is constantly evolving (see this just out book for example). Still, traditionally it could be conceptualized legally as an ability to keep certain things from entering one’s territory. To be clear, then, both Mexico and Canada are fully in their right to police their side of the border to prevent the entry of flows on their territory, including for example of drugs, weapons or unlawful migrants, as they have and will no doubt continue to do. Just as evidently, so is the US, which has a long history of doing just that. But one would struggle to locate sources of a general international legal obligation of the state to police its borders to prevent individuals and products from departing its territory into another state’s. 

The border is traditionally understood as a device to keep certain things (objects, persons, influences) out, not to keep these same things within one’s borders. At no point in the history of international law has the border been understood as imposing general obligations by states to prevent certain persons and objects from passing into the territory of other states. This is of course outside of special regimes that may stipulate otherwise. It has long been recognized, as it happens in the context of border relations between Canada and the US in the famous Trail Smelter case, that certain types of cross-border environmental harm can engage a state’s responsibility. There is arguably a special case against tolerating the presence of armed irregulars or terrorist groups that are hostile to a neighboring state on one’s territory and the UN’s sanctions regime specifically anticipates border control to suppress terrorist movement (this may explain the willingness in relations with Mexico to designate cartels as terrorist organizations).

When it comes to the issue of the day, the US has yet to articulate a legal case that Canada or Mexico are violating their international obligations. Indeed, the case is less clear when it comes to migrants and narcotics. The US, Mexico and Canada are parties to the Narcotics conventions, but these are silent on the question of cross border cooperation specifically. Indeed, as the US delegation in Vienna put it:

Under the 1988 Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, States Parties are required to carry out its treaty obligations in a manner consistent with the principles of sovereign equality and territorial integrity of other states.

Mexico, the US and Canada are all also parties to the United Nations Convention against Transnational Organized Crime and its Protocol to Prevent, Suppress and Punish Trafficking in Persons Especially Women and Children. The Protocol does indicate an obligation to monitor their borders specifically for trafficking, but this does not extend to migrants who are not trafficked. 

Whatever the political dynamics of Mexico and Canada acceding to US demands in terms of policing their borders to prevent access to US territory, then, their doing so reflects a potentially bizarre understanding wherein it is foreign states’ responsibility to police the borders of the US, effectively acting as de facto auxiliaries for US sovereignty. To proceed from such an obligation is to, fundamentally, encroach on the sovereignty of another state by forcing it to implement one’s sovereignty, effectively substituting for one’s own failings. Without more, this is a huge, illegitimate and illegal, ask. It is also, paradoxically, to debase one’s sovereignty in the process of loudly claiming respect for it. In short, it is not a priori either Mexico or Canada’s responsibility that fentanyl or migrants are seeping through the US border, any more it should be said, than it is the US’s responsibility to prevent various fluxes from entering Canada and Mexico. It would be another matter if Canada and Mexico were accused of deliberately pushing illegal migrants or drugs towards the US but there is no evidence to that effect, and any move to an “unwilling or unable” standard would end up producing an entirely bloated sense of third states’ obligations towards one’s borders.

The US border, then, precisely because the US is sovereign, is for the US to police. If the US wants to protect its borders it should, under international law and precisely because it is a sovereign state, do so at its own expense. One way of thinking of this is as the border not being unitary. There are, legally speaking, two borders typically overlapping but irreducible, each a political and legal construct of either state. Although there may physically be one border and only one border that is recognized internationally, for all intents and purposes each state conceives and is responsible for “its” border understood in its own constitutional and administrative terms. There is, in other words and legally speaking, a Canadian border with the US and a US border with Canada. The finality of each of these borders is to create a membrane (rather than a barrier) that filters incoming influxes from the other state. This is very much in line with a notion of sovereignty as a form of exclusive control on one’s territory subject only to voluntarily accepted international obligations. In that setup, it is for each state to police its borders as it sees fit, and certainly Canada and Mexico, needless to say, would have no business telling the US what it should allow to enter, let alone leave, its territory.

It is true that this membrane can also have a residual and ancillary function to retain outgoing fluxes but in a much more limited way and for the territorial state’s own ends. For example, typically borders serve to interdict escape by fugitives from justice from a state’s territory or to prevent the outward trafficking of archeological goods and antiques or protected species or certain weapons or maybe state secrets. This, however, they do on the state’s own self-constructed sovereign grounds or as a result of committing voluntarily to specific international obligations, and obviously not at the unilateral behest of any outside sovereign. Aside from such limited and self-assumed sovereign prerogative to use the border as a sort of outward flow capturing device, the regime of moving out from a state’s territory is very much structured by a principle of liberty. This is true both on sovereignty grounds (the state owes no a priori obligation to any other state to keep persons or goods “captive”) or international rights grounds (the state’s prerogative does not extend to preventing persons from legally departing its territory). 

In other words, in bending backwards to accommodate current US demands, Canada and Mexico are clearly going “above and beyond” anything that is required of them under general international law. None of this, of course, is exclusive of states agreeing between themselves, as sovereigns are occasionally wont to do, to mutually police shared borders to maximize reciprocal gains. There have been many initiatives of that kind in the context of US-Mexico relations including the Merida Initiative, the “Remain in Mexico” program, the Bicentennial Framework, and now a return of “Remain in Mexico” with various degrees of success even on narrowly defined immigration flux regulation. But such initiatives are concluded on the basis of mutual respect and negotiation as part of “friendly relations” between states.

Indeed, one of the paradoxes of the current moment is that, for all the huffing and puffing about US sovereignty, it dramatically underlines how one cannot be a sovereign alone and how one may well need the help and cooperation of allies treated as such in order to maximize the perceived benefits of one’s own sovereignty through respect for that of others. If that sounds remarkably like rediscovering a basic axiom of international law, it is because it is. Canada and Mexico can and maybe ought to be part of the solution to the US’s border problem but for their sovereign reasons and in exchange for help in dealing with their own border problems which include, notably in the case of Mexico, massive arms transfers that fuel the very drug crisis that the US is vehemently complaining about. But this is an entirely different framing, one that foregrounds voluntarily agreed commitments rather than unilateral fiat. 

Having said that and seen in broader perspective, Canada may well be getting a taste of what has been the most influential prescription for many states in the Global South on the receiving end of “externalization” of border arrangements. These sorts of arrangements have durably and paradoxically reshaped the policing of the border – that most cherished symbol of sovereignty – as in large part other states’ business as well, often for no better reason than the fact that they happen to be on migrants’ or drug traffickers’ routes. They manifest a form of “sovereign dumping”, essentially transferring the management of migratory flows and drug trafficking to other states on which one then leans heavily. This has become characteristic, for example, of the European Union’s highly problematic regulation of migratory flows and asylum demands. A related example would be the failed UK-Rwanda agreement. And “offshoring” of asylum and migration management has already long characterized the US’s relationship to its Southern neighbor(s). These are part, incidentally, of a much larger constellation of international approaches that includes outsourcing the repression of terrorism, the recycling of various forms of waste or even the environmental and social costs of producing goods in other states. 

Even when agreed by treaty, then, it is worth stressing that such arrangements are not a panacea and may involve little more than powerful states, although they may find convenient relays in other countries, “ganging up” to violate the rights of populations and individuals, often in exchange for dubious monetary or political compensation. In short, even heightened cooperation between the US and its partners is not guarantee that such agreements will pass muster, notably from the point of view of international human rights law, as the third safe state agreement between the US and Canada or the Remain in Mexico program already show. Still, building border regulation on a foundation of mutuality rather than assuming that other states should step up to remedy one’s own border failings would be a step towards good neighborliness, which is the least that Canada and Mexico can expect from their partner in the middle, and a minimum condition for actually tackling joint problems.