National position of the United States of America (2016)
This is the national position of the United States of America on international law applicable to cyber operations. The position  has been presented by Brian J. Egan, Legal Advisor of the US Department of State, during a speech at Berkeley Law School on 10 November 2016.
Applicability of international law
"Existing principles of international law form a cornerstone of the United States’ strategic framework of international cyber stability during peacetime and during armed conflict. The U.S. strategic framework is designed to achieve and maintain a stable cyberspace environment where all States and individuals are able to realize its benefits fully, where there are advantages to cooperating against common threats and avoiding conflict, and where there is little incentive for States to engage in disruptive behavior or to attack one another.
There are three pillars to the U.S. strategic framework, each of which can help to ensure stability in cyberspace by reducing the risks of misperception and escalation. The first is global affirmation of the applicability of existing international law to State activity in cyberspace in both peacetime and during armed conflict. The second is the development of international consensus on certain additional voluntary, non-binding norms of responsible State behavior in cyberspace during peacetime, which is of course the predominant context in which States interact. And the third is the development and implementation of practical confidence-building measures to facilitate inter-State cooperation on cyber-related matters."
"[..] remote cyber operations involving computers or other networked devices located on another State’s territory do not constitute a per se violation of international law. In other words, there is no absolute prohibition on such operations as a matter of international law. This is perhaps most clear where such activities in another State’s territory have no effects or de minimis effects.
Most States, including the United States, engage in intelligence collection abroad. As President Obama said, the collection of intelligence overseas is “not unique to America.” As the President has also affirmed, the United States, like other nations, has gathered intelligence throughout its history to ensure that national security and foreign policy decisionmakers have access to timely, accurate, and insightful information. Indeed, the President issued a directive in 2014 to clarify the principles that would be followed by the United States in undertaking the collection of signals intelligence abroad.
Such widespread and perhaps nearly universal practice by States of intelligence collection abroad indicates that there is no per se prohibition on such activities under customary international law. I would caution, however, that because “intelligence collection” is not a defined term, the absence of a per se prohibition on these activities does not settle the question of whether a specific intelligence collection activity might nonetheless violate a provision of international law.
Although certain activities—including cyber operations — may violate another State’s domestic law, that is a separate question from whether such activities violate international law. The United States is deeply respectful of other States’ sovereign authority to prescribe laws governing activities in their territory. Disrespecting another State’s domestic laws can have serious legal and foreign policy consequences. As a legal matter, such an action could result in the criminal prosecution and punishment of a State’s agents in the United States or abroad, for example, for offenses such as espionage or for violations of foreign analogs to provisions such as the U.S. Computer Fraud and Abuse Act. From a foreign policy perspective, one can look to the consequences that flow from disclosures related to such programs. But such domestic law and foreign policy issues do not resolve the independent question of whether the activity violates international law."
Prohibition of intervention
In certain circumstances, one State’s non-consensual cyber operation in another State’s territory could violate international law, even if it falls below the threshold of a use of force. This is a challenging area of the law that raises difficult questions. The very design of the Internet may lead to some encroachment on other sovereign jurisdictions. Precisely when a non-consensual cyber operation violates the sovereignty of another State is a question lawyers within the U.S. government continue to study carefully, and it is one that ultimately will be resolved through the practice and opinio juris of States.
Relatedly, consider the challenges we face in clarifying the international law prohibition on unlawful intervention. As articulated by the International Court of Justice (ICJ) in its judgment on the merits in the Nicaragua Case, this rule of customary international law forbids States from engaging in coercive action that bears on a matter that each State is entitled, by the principle of State sovereignty, to decide freely, such as the choice of a political, economic, social, and cultural system. This is generally viewed as a relatively narrow rule of customary international law, but States’ cyber activities could run afoul of this prohibition. For example, a cyber operation by a State that interferes with another country’s ability to hold an election or that manipulates another country’s election results would be a clear violation of the rule of non-intervention. For increased transparency, States need to do more work to clarify how the international law on non-intervention applies to States’ activities in cyberspace."
International human rights law
"The Internet must remain open to the free flow of information and ideas. Restricting the flow of ideas also inhibits spreading the values of understanding and mutual respect that offer one of the most powerful antidotes to the hateful and violent narratives propagated by terrorist groups.
That is why the United States holds the view that use of the Internet, including social media, in furtherance of terrorism and other criminal activity must be addressed through lawful means that respect each State’s international obligations and commitments regarding human rights, including the freedom of expression, and that serve the objectives of the free flow of information and a free and open Internet. To be sure, the incitement of imminent terrorist violence may be restricted. However, certain censorship and content control, including blocking websites simply because they contain content that criticizes a leader, a government policy, or an ideology, or because the content espouses particular religious beliefs, violates international human rights law and must not be engaged in by States." 
"From a legal perspective, the customary international law of state responsibility supplies the standards for attributing acts, including cyber acts, to States. For example, cyber operations conducted by organs of a State or by persons or entities empowered by domestic law to exercise governmental authority are attributable to that State, if such organs, persons, or entities are acting in that capacity.
Additionally, cyber operations conducted by non-State actors are attributable to a State under the law of state responsibility when such actors engage in operations pursuant to the State’s instructions or under the State’s direction or control, or when the State later acknowledges and adopts the operations as its own.
Thus, as a legal matter, States cannot escape responsibility for internationally wrongful cyber acts by perpetrating them through proxies. When there is information — whether obtained through technical means or all-source intelligence — that permits a cyber act engaged in by a non-State actor to be attributed legally to a State under one of the standards set forth in the law of state responsibility, the victim State has all of the rights and remedies against the responsible State allowed under international law.
The law of state responsibility does not set forth explicit burdens or standards of proof for making a determination about legal attribution. In this context, a State acts as its own judge of the facts and may make a unilateral determination with respect to attribution of a cyber operation to another State. Absolute certainty is not—and cannot be—required. Instead, international law generally requires that States act reasonably under the circumstances when they gather information and draw conclusions based on that information.
I also want to note that, despite the suggestion by some States to the contrary, there is no international legal obligation to reveal evidence on which attribution is based prior to taking appropriate action. There may, of course, be political pressure to do so, and States may choose to reveal such evidence to convince other States to join them in condemnation, for example. But that is a policy choice—it is not compelled by international law."
"[..]a State can always undertake unfriendly acts that are not inconsistent with any of its international obligations in order to influence the behavior of other States. Such acts—which are known as acts of retorsion—may include, for example, the imposition of sanctions or the declaration that a diplomat is persona non grata."
"The customary international law doctrine of countermeasures permits a State that is the victim of an internationally wrongful act of another State to take otherwise unlawful measures against the responsible State in order to cause that State to comply with its international obligations, for example, the obligation to cease its internationally wrongful act. Therefore, as a threshold matter, the availability of countermeasures to address malicious cyber activity requires a prior internationally wrongful act that is attributable to another State. As with all countermeasures, this puts the responding State in the position of potentially being held responsible for violating international law if it turns out that there wasn’t actually an internationally wrongful act that triggered the right to take countermeasures, or if the responding State made an inaccurate attribution determination. That is one reason why countermeasures should not be engaged in lightly.
Additionally, under the law of countermeasures, measures undertaken in response to an internationally wrongful act performed in or through cyberspace that is attributable to a State must be directed only at the State responsible for the wrongful act and must meet the principles of necessity and proportionality, including the requirements that a countermeasure must be designed to cause the State to comply with its international obligations—for example, the obligation to cease its internationally wrongful act — and must cease as soon as the offending State begins complying with the obligations in question.
I also should note that countermeasures taken in response to internationally wrongful cyber activities attributable to a State generally may take the form of cyber-based countermeasures or non-cyber-based countermeasures. That is a decision typically within the discretion of the responding State and will depend on the circumstances."
International humanitarian law (jus in bello)
The U.S. military must comply with the United States’ obligations under the law of armed conflict and other applicable international law when conducting cyber operations against ISIL, just as it does when conducting other types of military operations during armed conflict. To the extent that such cyber operations constitute “attacks” under the law of armed conflict, the rules on conducting attacks must be applied to those cyber operations. For example, such operations must only be directed against military objectives, such as computers, other networked devices, or possibly specific data that, by their nature, location, purpose, or use, make an effective contribution to military action and whose total or partial destruction, capture, or neutralization, in the circumstances ruling at the time, offers a definite military advantage. Such operations also must comport with the requirements of the principles of distinction and proportionality. Feasible precautions must be taken to reduce the risk of incidental harm to civilian infrastructure and users. In the cyber context, this requires parties to a conflict to assess the potential effects of cyber activities on both military and civilian infrastructure and users.
Even if they do not rise to the level of an “attack” under the law of armed conflict, cyber operations during armed conflict must nonetheless be consistent with the principle of military necessity. For example, a cyber operation that would not constitute an “attack,” but would nonetheless seize or destroy enemy property, would have to be imperatively demanded by the necessities of war. Additionally, even if a cyber operation does not rise to the level of an “attack” or does not cause injury or damage that would need to be considered under the principle of proportionality in conducting attacks, that cyber operation still should comport with the general principles of the law of war."
Voluntary, non-binding norms of responsible state behavior in peacetime
Internationally, the United States has identified and promoted four such norms:
- First, a State should not conduct or knowingly support cyber-enabled theft of intellectual property, trade secrets, or other confidential business information with the intent of providing competitive advantages to its companies or commercial sectors.
- Second, a State should not conduct or knowingly support online activity that intentionally damages critical infrastructure or otherwise impairs the use of critical infrastructure to provide service to the public.
- Third, a State should not conduct or knowingly support activity intended to prevent national computer security incident response teams (CSIRTs) from responding to cyber incidents. A State also should not use CSIRTs to enable online activity that is intended to do harm.
- Fourth, a State should cooperate, in a manner consistent with its domestic and international obligations, with requests for assistance from other States in investigating cyber crimes, collecting electronic evidence, and mitigating malicious cyber activity emanating from its territory.
It is important, however, to distinguish clearly between international law, on the one hand, and voluntary, non-binding norms on the other. These four norms identified by the United States, or the other peacetime cyber norms recommended in the 2015 UN GGE report, fall squarely in the voluntary, non-binding category. These voluntary, non-binding norms set out standards of expected State behavior that may, in certain circumstances, overlap with standards of behavior that are required as a matter of international law. Such norms are intended to supplement existing international law. They are designed to address certain cyber activities by States that occur outside of the context of armed conflict that are potentially destabilizing. That said, it is possible that if States begin to accept the standards set out in such non-binding norms as legally required and act in conformity with them, such norms could, over time, crystallize into binding customary international law. As a result, States should approach the process of identifying and committing to such non-binding norms with care."
- National position of the United States of America (2012)
- National position of the United States of America (2020)
Notes and references
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 2-3.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 11-13.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 13-14.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 16-17.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 17-20.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 20.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 21-22.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 8-10.
- Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 22-25.