I/A Court H.R., Juridical Condition and Rights of the Undocumented Migrants. Advisory Opinion OC-18/03 of September 17, 2003. Series A No.18.

Non official brief

This summary is also published in the website of the Council of Europe in the following link: https://www.venice.coe.int/files/Bulletin/B2004-1-e.pdf




1.  States have the general obligation to respect and ensure the fundamental rights. To this end, they must take affirmative action, avoid taking measures that limit or infringe a fundamental right, and eliminate measures and practices that restrict or violate a fundamental right.


2.  Non-compliance by the State with the general obligation to respect and ensure human rights, owing to any discriminatory treatment, gives rise to international responsibility.


3. The principle of equality and non-discrimination is fundamental for the safeguard of human rights in both international law and domestic law.


4. The fundamental principle of equality and non- discrimination forms part of general international law, because it is applicable to all States, regardless of whether or not they are a party to a specific international treaty. At the current stage of the development of international law, the fundamental principle of equality and non-discrimination has entered the domain of ius cogens.


5. The fundamental principle of equality and non- discrimination, which is of a peremptory nature, entails obligations erga omnes of protection that bind all States and generate effects with regard to third parties, including individuals.


6. The general obligation to respect and guarantee human rights binds States, regardless of any circumstance or consideration, including the migratory status of a person.


7. The right to due process of law must be recognised as one of the minimum guarantees that should be offered to any migrant, irrespective of his migratory status. The broad scope of the preservation of due process encompasses all matters and all persons, without any discrimination.


8. The migratory status of a person cannot constitute a justification to deprive him of the enjoyment and exercise of human rights, including those of a labor- related nature. When assuming an employment relationship, the migrant acquires rights that must be recognised and ensured because he is an employee, irrespective of his regular or irregular status in the State where he is employed. These rights are a result of the employment relationship.


9. The State has the obligation to respect and guarantee the labour human rights of all workers, irrespective of their status as nationals or foreigners, and not to tolerate situations of discrimination that are harmful to the latter in the employment relationships established between private individuals (employer- worker). The State must not allow private employers to violate the rights of workers, or the contractual relationship to violate minimum international standards.


10. Workers, being possessors of labour rights, must have all the appropriate means to exercise them. Undocumented migrant workers possess the same labour rights as other workers in the State where they are employed, and the latter must take the necessary measures to ensure that this is recognised and complied with in practice.


11. States may not subordinate or condition observance of the principle of equality before the law and non-discrimination to achieving their public policy goals, whatever these may be, including those of a migratory character.




Pursuant to Article 64.1 ACHR (American Convention on Human Rights – hereinafter “American Convention”), the State of the United Mexican States (hereinafter “Mexico”) requested on 10 May 2002 that the Court exercise its advisory jurisdiction and emit an opinion on the following matters:


In the context of the principle of equality before the law embodied in Article II of the American Declaration on the Rights and Duties of Man (hereinafter “American Declaration”), Article 24 of the American Convention, Article 7 of the Universal Declaration on Human Rights and Article 26 of the International Covenant on Civil and Political Rights (hereinafter “ICCPR”): 


1. Can an American State establish in its labour legislation a distinct treatment from that accorded legal residents or citizens that prejudices undocumented migrant workers in the enjoyment of their labour rights, so that the migratory status of the workers impedes per se the enjoyment of such rights?


 2.1 Should Article 2.1 of the Universal Declaration of Human Rights, Article II of the American Declaration on the Rights on Duties of Man, Articles 2 and 26 ICCPR, and Article 1 ACHR and Article 24 ACHR be interpreted in the sense that an individual’s legal residence in the territory of an American State is a necessary condition for that State to respect and ensure the rights and freedoms recognised in these provisions to those persons subject to its jurisdiction?


2.2 In the light of the provisions cited in the preceding question, can it be considered that the denial of one or more labour right, based on the undocumented status of a migrant worker, is compatible with the obligations of an American State to ensure non-discrimination and the equal, effective protection of the law imposed by the above- mentioned provisions?


Based on Article 2.1, 2.2 and Article 5.2 ICCPR,


3. What would be the validity of an interpretation by any American State which, in any way, subordinates or conditions the observance of fundamental human rights, including the right to equality before the law and to the equal and effective protection of the law without discrimination, to achieving migration policy goals contained in its laws, notwithstanding the ranking that domestic law attributes to such laws in relation to the international obligations arising from the International Covenant and other obligations of international human rights law that have an erga omnes character?


In view of the progressive development of international human rights law and its codification, particularly through the provisions invoked in the instruments mentioned in this request,


4.  What is the nature today of the principle of non- discrimination and the right to equal and effective protection of the law in the hierarchy of norms established by general international law and, in this context, can they be considered to be the expression of norms of ius cogens? If the answer to the second question is affirmative, what are the legal effects for the OAS Member States, individually and collectively, in the context of the general obligation to respect and ensure, pursuant to Article 2.1 ICCPR, compliance with the human rights referred to in Articles 3.l and 17 of the OAS Charter?