Article 2 of the Slavery Convention states: "The High Contracting Parties undertake, each in respect of the territories placed under its sovereignty, jurisdiction, protection, suzerainty or tutelage, to prevent and suppress the slave trade and to bring about, progressively and as soon as possible, the complete abolition of slavery in all its forms." This establishes an obligation on States Parties to abolish slavery in law and practice.

The preamble to the Supplementary Convention recalls that the Universal Declaration of Human Rights "states that no one shall be held in slavery or servitude and that slavery and the slave trade shall be prohibited in all their forms." Article 3 requires that "the act of conveying or attempting to convey slaves from one country to another... shall be a criminal offence under the laws of the States Parties." States must criminalize slave trading and related practices in domestic law.

The UN Treaty Collection page for the Slavery Convention records the status of ratifications, accessions and successions for each State. The table lists numerous States with dates of accession or ratification, showing how they became parties to the convention and accepted its obligations to suppress slavery. This official register indicates which countries are legally bound by the Convention’s provisions.

The certified text of the Supplementary Convention specifies that "This Convention shall be open until 1 July 1957 for signature by any State Member of the United Nations or of a specialised agency" and that it "shall be subject to ratification" with instruments deposited with the UN Secretary-General. It further notes that the Convention enters into force for each State "on the date of deposit of the instrument of ratification or accession", meaning domestic legal obligations against slavery-like institutions arise only when a State becomes a party.

Article 2 of the Slavery Convention signed at Geneva on 25 September 1926 states: "The High Contracting Parties undertake, each in respect of the territories placed under its sovereignty, jurisdiction, protection, suzerainty or tutelage, to prevent and suppress the slave trade and to bring about, progressively and as soon as possible, the complete abolition of slavery in all its forms." This convention, later supplemented by the 1956 Supplementary Convention, became a core international legal instrument obliging states to abolish and prohibit slavery in law and practice.

The prohibition of slavery is widely regarded in contemporary international law as a jus cogens norm, that is, "one of the few jus cogens norms of international law carrying obligations erga omnes" meaning that slavery has achieved universal legal opposition and is prohibited for all states under international law.[3] This reflects that de jure chattel slavery – the legal reduction of persons to the status of things in law – is no longer lawful under modern international legal standards.[3]

Article 4 of the European Convention on Human Rights provides that "No one shall be held in slavery or servitude" and that "No one shall be required to perform forced or compulsory labour." The European Court of Human Rights has developed extensive case law interpreting this article, requiring member states not only to refrain from slavery but also to criminalise and effectively prosecute slavery, servitude and forced labour within their jurisdictions.

Our recent investigation indicates that nearly 50% of the countries worldwide have not yet criminalized the act of enslaving another individual. Notably, our research reveals that: - 94 states (49%) lack criminal laws against slavery In these nations, there are no criminal laws to hold individuals accountable for these severe forms of exploitation. Thus, the assertion that slavery is illegal everywhere is far from accurate.

Article 4 of the Universal Declaration of Human Rights provides: "No one shall be held in slavery or servitude; slavery and the slave trade shall be prohibited in all their forms." As a UN General Assembly declaration, it sets a universal standard that slavery should be prohibited everywhere, though it is not itself a treaty creating direct binding obligations like a convention does.

Historic laws that allowed slavery have been scrapped worldwide, but in many countries it hasn't been explicitly criminalised. In 94 countries, a person cannot be prosecuted for enslaving another human being. "Slavery is far from being illegal everywhere and we hope our research will move the conversation beyond this popular myth," said Katarina Schwarz, a researcher at the University of Nottingham's Rights Lab, which led work on the slavery database.

An EBSCO research overview of UN anti-slavery efforts notes that the United Nations ratified the 1926 Slavery Convention on October 23, 1953, and that the Universal Declaration of Human Rights in 1948 prohibited slavery and the slave trade, but that "enforcement remained a challenge" and slavery persisted in several countries such as Ethiopia, Liberia and Saudi Arabia after World War II. This illustrates the gap between legal prohibition and practice.

Walk Free’s Global Slavery Index notes that although most countries have taken steps against human trafficking, significant legal gaps remain around slavery and related practices. The Index highlights that state‑imposed forced labour is practiced in at least 17 countries and that legal loopholes in many jurisdictions enable forced labour and other forms of modern slavery to occur despite formal prohibitions on paper. This underscores that the existence of some legal prohibitions does not eliminate slavery‑like practices in practice.

Katarina Schwarz of the University of Nottingham Rights Lab explains that the Antislavery in Domestic Legislation database systematically coded national laws to assess compliance with international obligations to prohibit slavery. The research concluded that while legal ownership of persons has been abolished globally, "in almost half of the world’s countries, there is no legal framework to punish slavery or slave trade" and that "the assertion that slavery is illegal everywhere is far from accurate." The authors argue that mere abolition without criminalisation leaves a major enforcement gap.

The U.S. Constitution’s Thirteenth Amendment states: "Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction." Senator Jeff Merkley’s commentary notes that "we abolished slavery — except as punishment for a crime" and that "right now, there are roughly 1.2 million people in prisons across the US who can be and often are legally enslaved." He has proposed an "Abolition Amendment" that would remove the punishment exception so that "neither slavery nor involuntary servitude may be imposed as punishment for a crime."

This study describes the development of the international legal regime against slavery and human exploitation, outlining three eras of abolition from 1890–1966 and beyond.[5] It explains that international instruments such as the 1926 Slavery Convention and subsequent treaties prohibit both "de jure" slavery (legal ownership) and "de facto" slavery (exercise of powers attaching to ownership), with the High Court of Australia in The Queen v Tang clarifying that the definition of slavery covers both status (a legal concept) and condition (de facto situations).[5] The article underscores that international law requires states to prohibit slavery in all its forms, but domestic implementation varies.[5]

The Charter of Fundamental Rights of the European Union "banned slavery, forced labor and human trafficking," establishing a regional human-rights instrument that explicitly outlaws such practices for EU member states.[6] This reflects that, at least within the EU legal order, slavery and related institutions are clearly illegal.[6]

Although slavery is illegal in every country in the modern world, it still exists, and even on the narrowest definition of slavery it's likely that there are far more slaves now than there were victims of the Atlantic slave trade. The last country to abolish slavery was the African state of Mauritania, where a 1981 presidential decree abolished the practice; however, no criminal laws were passed to enforce the ban. In August 2007 Mauritania's parliament passed legislation making the practice of slavery punishable by up to 10 years in prison.

The Timeline of abolition of slavery and serfdom notes that "Mauritania was the last nation at the time to abolish slavery: the practice became nominally illegal worldwide until Afghanistan legalized it in January 2026." It adds that today "no country in the world openly allows slavery of non-prisoners, but the practice continues in many locations around the world." This reflects the distinction between formal legal abolition and the continued existence of slavery and slavery-like practices in reality.

In 1865, the United States ratified the 13th Amendment to the United States Constitution, which banned slavery and involuntary servitude "except as punishment for a crime whereof the party shall have been duly convicted", providing a legal basis for slavery, now referred to as penal labor, to continue in the country. Mauritania has a long history with slavery. Chattel slavery was formally made illegal in the country but the laws against it have gone largely unenforced. It is estimated that around 90,000 people (over 2% of Mauritania's population) are slaves.

The University of Minnesota’s human rights library provides treaty ratification tables, including one for South Africa that lists the Slavery Convention (signature/ratification/entry into force dates) and the Protocol amending the Slavery Convention. These tables show how specific countries have ratified or acceded to slavery-related conventions, indicating adoption of legal obligations to abolish slavery under international law.

The Office of the UN High Commissioner for Human Rights explains that under international human rights law, slavery and the slave trade are prohibited absolutely. Instruments such as the Universal Declaration of Human Rights (Article 4), the International Covenant on Civil and Political Rights (Article 8), and the Slavery Convention collectively establish a universal ban on slavery, obliging states to prohibit and eliminate it. However, OHCHR reporting also acknowledges that despite these legal norms, millions of people remain in situations of servitude, forced labour and other slavery‑like practices globally.

Mauritania was the last country in the world to outlaw slavery in 1981. It wasn’t until 2007 that the government, facing international pressure, passed a law that would prosecute slave owners. Still, since then, the country has only prosecuted three cases of slavery, and according to the 2016 GSI, 1.06% of the population still live in bondage, with many children being born into slavery.

The Wikipedia entry on the 1926 Slavery Convention summarizes that its objective is to "confirm and advance the suppression of slavery and the slave trade" and that it was extended by the 1956 Supplementary Convention. It states that as of 2013, "there are 99 countries that have signed, acceded to, ratified, succeeded to, or otherwise committed to participation" in the Convention as amended. The list demonstrates that some UN member states are not parties to the Convention itself, even though slavery is widely prohibited under other instruments and customary law.

However, only half (51%) have laws that specifically prohibit slavery and the slave trade. What's more, only two of 193 have laws that specifically criminalize slavery. The data show that many countries lack comprehensive legal frameworks directly targeting slavery, even though they may have broader human trafficking or labor laws.

The International Maritime Organization’s "Status of Conventions" page provides an example of how UN-related bodies track ratifications and implementation of international conventions by State, including those addressing criminal activities like trafficking by sea. It shows that not all conventions achieve universal ratification and that the legal status of particular practices can vary between countries until such ratification occurs.

The UNODC page on the UN Convention against Corruption describes a similar treaty-based approach to outlawing specific practices, giving ratification status by country and emphasizing that the Convention "requires States to implement several anti-corruption measures" once they become parties. This parallels how slavery-related conventions function: legal obligations arise from ratification, and universal norms do not automatically mean every state has identical domestic legislation at the same time.

The 13th Amendment of the U.S. Constitution clearly permits slavery or involuntary servitude as a consequence of a criminal conviction. It states that slavery and involuntary servitude are prohibited "except as a punishment for crime whereof the party shall have been duly convicted". This constitutional language is often cited as allowing penal labor and related practices within the United States legal system.

A Reddit discussion on a map of "Year of abolition of slavery by country" observes that "there are still numerous de facto slaves in Mauritania, even though the abolition law was enacted in 1981" and comments that slavery "maybe [is] abolished on paper, but it’s still rife across Africa, especially in Mauritania."[9] The thread distinguishes formal legal abolition from ongoing practices resembling slavery.[9]

Contemporary human rights scholarship and NGO reporting generally hold that slavery is prohibited under international law and under the domestic law of virtually all countries, through constitutional provisions, criminal codes, or specific anti-slavery statutes. However, researchers also note that in some jurisdictions, certain forms of slavery-like practices have historically lacked explicit criminalization or have only recently been addressed, underscoring the need to distinguish between formal legal prohibition and ongoing practices.

The article on the legal framework of slavery in the Dutch Republic discusses how Roman law and contemporary legislation were used to regulate the lives of enslaved individuals, indicating that historically slavery was explicitly structured and permitted within legal systems.[10] It contrasts that historical legal status with the modern international regime in which slavery is formally prohibited and considered incompatible with current legal orders.[10]

Maybe abolished on paper, but it’s still rife across Africa, especially in Mauritania. Commenters note that while legal abolition dates exist for each country, actual practices of slavery and bondage continue. This discussion highlights the distinction between formal legal status and real-world persistence of slavery.