Peacetime espionage describes the state-sponsored theft of confidential information for national security purposes and there are almost daily reports detailing states’ involvement in this activity (some of which are rather bizarre: see here (‘spy pigeon’), here (‘spy vulture’) and here (‘spy whale’). Rates of espionage have risen dramatically since the advent of cyberspace and the potential for cyber-enabled spying.

While states usually regulate espionage through national criminal law, the conventional wisdom among international lawyers is that ‘international law is silent on the subject of espionage’ (Brown, 621). According to this view, espionage is ‘neither legal nor illegal under international law’ (Radsan, 596).

This conclusion should come as a surprise.

While there is no direct and specific ‘international law of espionage’ (and only law ‘on’ or ‘about’ it), it is an inherently intrusive activity and, as such, it is likely to run into conflict with a number of rules of international law which, fundamentally, have the principle of the sovereign equality of states as their normative source. This begs the question as to why international lawyers maintain the fiction that there is no interaction between international law and espionage, the answer to which is relatively straightforward: these lawyers perceive espionage to be an essential national security tool because it allows states to identify the threats and dangers proliferating within the world order.

Understandably so.

Since the Snowden revelations in 2013 – and in particular the determination by a number of states that the USA’s espionage activities violated various primary rules of international law (for a discussion see Buchan) – international lawyers have been unable to maintain the position that espionage is unconstrained by international law. Nowadays, international lawyers concede that general principles of international law (such as the principle of territorial sovereignty) and specialised regimes (such as diplomatic law and the law of the sea) prohibit espionage. Yet, determined to preserve the capacity of states to conduct espionage, these lawyers have redrawn the battle-lines. In particular, they contend that permissive espionage exceptions have emerged in relation to these prohibitive rules of international law under customary international law (CIL) (as an example, see Deeks, 305).

Customary International Law

The CIL calculus is well known. Article 38(1)(b) of the Statute of the International Court of Justice (ICJ) 1945 stipulates that CIL develops on the back of state practice and opinio juris, a methodological approach that has been confirmed by numerous ICJ decisions. The calculus for identifying CIL is stringent: state practice must be ‘widespread’ and ‘representative’ (North Sea Continental Shelf Cases, para 73) and, in addition, it must be accompanied by assertions that such conduct is lawful under CIL. Indeed, this approach is particularly strict when it comes to identifying an exceptionto an otherwise prohibitive rule. As the ICJ explained in the Nicaraguacase, state practice deviating from an established rule should be generally regarded as a violation of that rule rather than signalling the emergence of an exception to it. Yet, recognising this approach may stagnate the development of CIL, the ICJ accepted that exceptions to rules can emerge where a state expressly claims an exception under CIL and this claim ‘is shared in principle by other states’ (Nicaragua, para 207). Can this be said with regard to espionage exceptions? This question will be answered over two posts: the first post concentrates on the element of state practice, and the second post focuses upon the requirement of opinio juris.

State Practice

There can be no doubt that states engage in espionage in violation of primary rules of international law. Equally clear is the fact that this state practice is widespread within, and representative of, the international society. However, espionage raises new (and largely unresolved) questions as to what types of state conduct can be selectedas state practice for the purpose of CIL development.

As the International Criminal Tribunal for the Former Yugoslavia (Tadic, para 99) and the International Law Association (Committee on Customary Law, Principle 5) have noted, state conduct committed in secret does not qualify as state practice in the CIL equation. The reason for this is clear: CIL develops according to an iterative process of claim and counter-claim between sovereign states. State conduct committed in secret is hidden from international scrutiny and, as such, it prevents other states from expressing their sovereign views as to the legal status of that activity; that is, states are unable to accept the rule and contribute towards its customary formation; or reject the rule and frustrate its customary development; or dissent from the rule and identify themselves as persistent objectors. Secret state conduct therefore undermines the principle of state sovereignty and, for this reason, it is methodologically irrelevant to the identification of CIL. This has important implications for the existence of customary espionage exceptions because espionage is an activity that is (almost by definition) conducted in secret (see Navarrete and Buchan, 919).

What about state involvement in espionage that is leaked to the public, as was the case with the Snowden revelations where US documents authorising espionage were widely published by The Guardian newspaper? If, as said, CIL forms according to a consensual process of claim and response between sovereign states, leaked state conduct cannot amount to state practice unlessthe impugned state publicly acknowledges that conduct as its own. In short, where a state fails to acknowledge its espionage operations, there is no ‘claim’ by that state that the espionage operation is lawful by virtue of a customary espionage exception. This being said, leaks may force a state to publicly defend its espionage activities, or may stimulate a debate among other states on the topic of espionage. If these discussions involve states publicly acknowledging their espionage activities, this will amount to state practice. While the Snowden revelations did trigger a lively debate on espionage within the world order, including public admissions by states that they engage in espionage, this state practice is still pocketed and piecemeal and it is not of sufficient quantity to found a rule of customary international law.

Part II of Why Silence Isn’t (Always) Golden: Espionage Exceptions under Customary International Law will be published on 10 October 2019.