Groningen Journal of International Law

International Law Under Construction

The Horizontal Effect of International Human Rights Law

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By Lottie Lane |

This blog post summarises some of the main findings of the author’s PhD thesis, entitled ‘The Horizontal Effect of International Human Rights Law: Towards a Multi-Level Governance Approach’. The findings are taken from an extensive comparative analysis of the extent to which international human rights law is applied to non-State actors (i.e. the horizontal effect of human rights) in jurisprudence at the international, regional and national levels.


Many non-State actors are in a position to greatly affect individuals’ enjoyment of their human rights. This is particularly true of non-State entities carrying out public functions or with control over an area of territory or even in a position to direct States in the adoption and implementation of certain domestic laws and policies. However, single individuals may also be in a position of relative power over other individuals, due perhaps to their gender, their position within a family, or their membership of a certain race or social class. This places them in a position where they can more easily affect another individual’s rights. Despite this, non-State actors do not currently have any direct obligations under international human rights law; the current international human rights law framework remains State-centric, with the responsibility for protecting individuals’ human rights from the harmful conduct of non-State actors lying in the positive obligations of the State.

Introducing horizontal effect

A fundamental question when looking at non-State actors and human rights is: what is the ‘horizontal effect’ of international human rights law? Typically, horizontal effect is considered to be either direct or indirect. Direct horizontal effect entails the direct application of international human rights between non-State actors and therefore whose rights have been negatively affected by non-State actors to hold them directly accountable – to bring a legal complaint against the non-State actor for not complying with human rights standards. Within international human rights law, this is not yet possible, although significant moves have been made towards it in some contexts (for an overview, see here).

Under indirect horizontal effect, which has evolved in the absence of direct horizontal effect, States are typically held directly and internationally responsible for the conduct of non-State actors that interfere with the enjoyment of human rights. This is possible because States’ international obligation to protect human rights often requires them to place direct obligations (or at least standards of behaviour) on non-State actors at the national level. It can be argued, then, that non-State actors are required, by international human rights law, to conduct themselves in a human rights-compliant manner (resulting in indirect horizontal effect). Other forms of indirect horizontal effect are introduced below.

Findings: Horizontal effect at the international level

The most significant examples of horizontal effect at the international level can be found in the UN human rights treaty bodies’ general comments and views on individual communications. The jurisprudence of five treaty bodies was analysed: the Human Rights Committee, the Committee on Economic, Social and Cultural Rights, the Committee against Torture, the Committee on the Elimination of Racial Discrimination and the Committee on the Elimination of Discrimination against Women. Despite the lack of direct horizontal effect in the relevant treaties, each body examined deals with situations in which interference with human rights was caused by non-State actors. There are many instances in which the treaty bodies uphold States’ obligation to protect human rights from the harmful conduct of non-State actors, although the standards of this obligation differ depending on which non-State actor has caused the harm.

Different standards have been applied, for example, in relation to: individuals; private businesses; private companies or institutions carrying out public functions delegated to them by the State; non-State armed groups; and international organisations. Jurisprudence involving individuals generally centres on due diligence – the obligation to investigate, prevent and punish human rights interference by non-State actors (see L. K. v The Netherlands; CteeESCR General Comment Nos. 5 and 14). Very similar standards are upheld in relation to private businesses, including banks and insurance boards (see Habassi v Denmark, B.d.B. et al. v The Netherlands, CteeESCR General Comment No. 24). In cases concerning private companies and institutions carrying out public functions (e.g. Cabal and Pasini v Australia; Alyne da Silva Pimentel Teixeira (deceased) v Brazil) the treaty bodies focused on attributing their conduct to the State, also upholding a State obligation to regulate such actors. In relation to non-State armed groups, different approaches are taken depending on the group’s control over territory (contrast, for example, S. V. et al. v Canada with Sadiq Shek Elmi v Australia). Finally, reference to possible direct obligations of international organisations were made by the Committee on Economic, Social and Cultural Rights in its General Comments Nos. 14 and 15.

Findings: Horizontal effect at the regional and national levels

At the regional level – the European, Inter-American and African human rights systems – there appears to be an increasing willingness to engage with the possibility of human rights violations by non-State actors within case law, with a particular focus on due diligence (although the terminology differs according to which actor is being discussed and within which regional system).

At the national level, horizontal effect is allowed for by theThe Act does not contain human rights standards itself but incorporates the European Convention of Human Rights (ECHR) into UK domestic law. In the UK’s jurisprudence, two main ways in which human rights standards can be upheld vis-à-vis non-State actors were found. First, Section 6 of the Human Rights Act allows, under certain situations, non-State actors to be considered ‘public authorities’ and therefore required to comply with human rights as laid down in the ECHR. In practice, the case law on this has been inconsistent and has failed to clarify the precise circumstances under which a non-State actor can be considered a public authority (see, for example, the cases of R (on the application of Heather and others) v Leonard Cheshire Foundation and another, Aston Cantlow and Wilmcote with Billesley Parochial Church Council v Wallbank and another and YL v Birmingham City Council). Second, due to the obligation of domestic courts in the UK not to act in a way that is contrary to the ECHR, the Human Rights Act has allowed for human rights standards to be incorporated into common law cases between two non-State actors. The approach has been applied with regard to various human rights found in the ECHR, leading to different outcomes.

Findings: Overview of horizontal effect of international human rights law

Overall, three kinds of indirect horizontal effect were found in the practice of international human rights at the international, regional and national levels: (1) diagonal indirect horizontal effect; (2) categorical indirect horizontal effect; and (3) value-driven indirect horizontal effect.

  • Diagonal indirect horizontal effect

Diagonal indirect horizontal effect involves the State’s positive obligation to protect individuals being applied to create indirect international obligations for non-State actors and is the most common approach adopted. At the international level and within the Inter-American human rights system much emphasis is placed on States’ due diligence obligations, notably those to prevent, investigate and punish non-State actors that interfere with the enjoyment of human rights. A specific State obligation to regulate certain non-State actors to ensure that they respect human rights has also developed at the international and regional levels. This obligation could also be considered as an indirect obligation for non-State actors to respect human rights.

  • Categorical indirect horizontal effect

Categorical indirect horizontal effect applies in situations where a non-State actor can be re-categorised as a State actor for the purposes of human rights. This includes situations where a non-State actor has taken on a quasi-governmental functions or even status. Although common at the national level under the UK’s Human Rights Act, this method has been applied to a much more limited degree at the international level (e.g. in the case of Sadiq Shek Elmi v Australia) and has not been applied at all at the regional level.

  • Value-driven indirect horizontal effect

Value-driven indirect horizontal effect has also been applied almost exclusively at the national level (with limited evidence within the European human rights system). Under this approach, the laws being applied are not human rights laws per se, but rather private laws that are interpreted so as to be compliant with the human rights found in the ECHR (see, for instance, Campbell v Mirror Group Newspapers Ltd and Douglas v Hello! Ltd (No.3)); the values of human rights influence the application of laws that apply directly between two private parties.

A brief critique of the findings

Ultimately, despite these three methods allowing for a degree of horizontal effect of international human rights law, the protection that they afford individuals is insufficient. The application/use of each model on all levels is inconsistent and sometimes incoherent. Sometimes the inconsistency stems from the language used by the relevant body, despite the concrete standards and outcomes of the cases being very similar to one another, such as, for example, the use or non-use of the terms ‘due diligence’ and the ‘obligation to protect’ human rights. On other, more worrisome occasions, the inconsistency or incoherence stems from the content of the standards applied (e.g. the test used to determine whether an actor is a hybrid public authority under the Human Rights Act 1998). There is a general lack of willingness and ability (in the sense that monitoring bodies and courts must act within the confines of their mandates and legal systems in which they operate) to actively engage with theoretical concepts and scholarly opinion relating to horizontal effect and to use particular terminology.

This further obfuscates the clarity that such cases could bring to the issue of horizontal effect. As it stands, although the three models of indirect horizontal effect can be clearly seen in jurisprudence, it remains unclear for individuals, non-State actors and to some extent also States exactly what conduct can be and is expected of different kinds of non-State actors vis-à-vis human rights. Indeed, the majority of practice at the international and regional levels has focused almost exclusively on the standards of behaviour expected of States without explaining the standard of conduct expected of non-State actors. This means that individuals may not be aware of when their human rights have been violated, or whether they are able to file a complaint against the State for the harm they have suffered. Additionally, at least at the international and regional levels, non-State actors may not be aware of the conduct that is expected of them. It also seems as though monitoring bodies and courts have actually gone as far as they can within the confines of their mandates and legal frameworks in individual cases to achieve more protection for human rights. The methods being used to achieve indirect horizontal effect have not actually changed much over the years in which they have been applied, although the UN Committee on Economic, Social and Cultural Rights seems to be considerate of current developments, having adopted a general comment on businesses and human rights.

Perhaps human rights law has reached a stalemate with this issue – further progress in holding non-State actors responsible for the harm they cause to human rights may not be made in international human rights law as it currently stands. Much progress remains to be made, however, especially considering the inability of indirect horizontal effect to provide consistent, comprehensive protection for individuals from the harmful conduct of non-State actors. This leaves us with two main avenues for moving forwards – expanding the scope of international human rights law to apply to non-State actors, or looking outside the legal framework to improve the conduct of non-State actors for what concerns human rights. A follow-up post will summarise the author’s ideas on how to strengthen efforts being taken beyond the legal framework by taking a governance approach to non-State actors and human rights.


Lottie Lane is an Assistant Professor at the Department of Transboundary Legal Studies, University of Groningen. Her PhD research dealt with the horizontal effect of international human rights from a law and governance perspective. Lottie’s wider research interests and publications include business and human rights, the human rights responsibilities of NGOs and non-State armed groups, and the role of human rights and non-State actors in disaster governance.


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