The right to privacy has existed in international law since 1966, but the improved capacity of governments’ surveillance and spying software in the past decade has made the right to privacy especially pertinent. Two issues have become particularly important: whether the right applies to all humans irrespective of their geographic location and what States’ obligations in respecting individuals’ right to privacy actually entail. International law is an evolving body of law: in 2020, participating States’ obligations under the ICCPR require that these States afford the right to privacy to all people. Despite this, States are not restricted from conducting surveillance for national security.
First, all States are legally obliged to afford the people in their jurisdiction a right to privacy. Article 17(1) of the International Covenant on Civil and Political Rights (ICCPR) requires States to uphold the right to privacy to all people, irrespective of whether they are in their territorial jurisdiction. 173 States have signed this treaty, and jurisprudence interpreting the ICCPR has confirmed that the right applies extraterritorially – that is, States are legally compelled to afford people the right contained in this article irrespective of whether they are in their territorial jurisdiction.
Furthermore, the remaining States that are non-signatories are likely also obliged to uphold the right to privacy, on the basis that the right to privacy has crystallized as Customary International Law. Customary International Law is a source of International Law not contained in the treaty necessarily, but nonetheless legally obligatory on States. The International Court of Justice has articulated that Customary International Law is formed by the coexistence of opinio juris and State Practice. Opinio juris exists where there is evidence that States believe their actions are obligatory due to the existence of a rule. The second element is State Practice. State practice must be geographically widespread and legally and politically representative.
The prevalence of the right to privacy in many treaties, combined with the acknowledgement of this right in many domestic laws and the standardized international value of privacy, indicates that this right has sufficient state practice and opinio juris to have crystalized as Customary International Law. A counterargument to this point is that many States continuously conduct invasive mass surveillance. However, rather than suggesting that the right to privacy is overall not contained in Customary International Law, it merely suggests that the content of the right per custom does not extend to prohibiting surveillance.
The permissibility of surveillance also likely extends to the right to privacy under the ICCPR. While privacy under the ICCPR has not been explicitly defined by any interpretative body, the Human Rights Council has interpreted Article 17(1) of the ICCPR as requiring States to take active measures to ensure any interference with privacy complies with the principles of legality, proportionality, and necessity. The standard for these principles is developed in the International Principles on the Application of Human Rights Law to Communications Surveillance. Limiting the right to privacy must be prescribed by law and for a legitimate aim, must be adequately appropriate to fulfilling the legitimate aim, and proportionately intrusive to achieving the legitimate aim. The actions burdening the right to privacy must be completed by a competent judicial authority, governed by lawful procedures, and those whose communications are being surveyed should be notified. This indicates that government surveillance is entirely legally permissible, even if it is justifiable and compatible with domestic law. Governments invoking national security as a justification for conducting surveillance on individuals is, in most cases, acceptable.
All States are legally obliged to afford their citizens the right to privacy. However, if there are reasonable national security reasons for carrying out surveillance, both Customary International Law and the ICCPR effectively allow for States to do so.
 The United Nations General Assembly. 1966. “International Covenant on Civil and Political Rights.” Treaty Series 999 (December): 171, article 17(1).
 Liberty and others v United Kingdom  48 ECtHR 1, 13.
 International Court of Justice. North Sea Continental Shelf Cases; (Federal Republic of Germany/Denmark; Federal Republic of Germany/Netherlands). [Leiden] :[A. W. Sijthoff], 19681969, 77.
 Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits)  ICJ Rep 14, 95.
 ICJ, North Sea Continental Shelf, 77.
 Alexandra Rengel, “Privacy as an International Human Right and the Right to Obscurity in Cyberspace,” Groningen Journal of International Law, no 2. Issue (2014): 42, https://www.researchgate.net/publication/328960219_Privacy_as_an_International_Human_Right_and_the_Right_to_Obscurity_in_Cyberspace.
 Human Rights Council, Report of the Office of the United Nations High Commissioner for Human Rights, UN Doc A/HRC/39/29, 30 June 2014.
 Electronic Frontier Foundation, “International Principles on the Application of Human Rights Law to Communications Surveillance”, website May 2014, https://www.ohchr.org/documents/issues/privacy/electronicfrontierfoundation.pdf.
 “International Principles”.
 “International Principles”.