OXFORD, England — CAN you have too many rights? It sounds like a bizarre notion. But in the case of migrants, there may be something to it.

In 1990, the United Nations General Assembly adopted the International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families, which stipulated a comprehensive set of civil, political, economic and social rights for migrants, including those living or working abroad illegally. But 23 years later, there is no denying the failure of the convention to protect those rights.

News of the mistreatment of migrants seems to arrive every few months. In September, an investigation by the British newspaper The Guardian exposed numerous deaths among Nepalese workers on World Cup construction sites in Qatar. Earlier this month, more than 400 migrants rioted after a bus hit and killed an Indian worker in Singapore, where large numbers of low-skilled migrants are employed under deplorable working and living conditions.

There is a wide gap between the rights of migrant workers in theory and practice, especially in the case of those employed in lower-wage jobs. Under most existing temporary migration programs in North America and Europe, for example, migrants do not enjoy the degree of access to welfare benefits demanded by the convention. In the Persian Gulf nations, more alarmingly, it is common practice for employers to retain migrant employees’ passports to make sure they cannot “escape.”

Why has the 1990 convention failed? The main problem is that it has proved unacceptable to essentially all major migrant-receiving countries. Fewer than 50 countries have signed and ratified it; most of them are predominantly migrant-sending rather than migrant-receiving. This makes the convention the least ratified of all the major international human rights treaties.

Many high-income countries have been explicit about why they have not ratified the convention: The comprehensive set of rights that it stipulates conflicts with their own policies for regulating immigration through temporary migration programs. These policies typically restrict some of the rights of migrants, such as the rights to free choice of employment, equal access to social welfare benefits and family reunification.

In Canada, for example, government officials have said that a key obstacle to the ratification of the convention is the concern that it could be incompatible with Canada’s growing temporary migration programs for low-skilled migrant workers. Similarly, Britain has stated that a critical reason for not ratifying the convention is the associated costs for its welfare state and the adverse effect on the government’s ability to properly manage labor immigration.

These cases are typical. As my research shows, labor immigration policies of high-income countries are characterized by a trade-off between openness and rights: More open admission policies tend to be associated with greater restrictions of migrant rights, especially in the case of lower-skilled workers.

We need to develop a new approach to the global protection of migrant workers that is based on a clear understanding about what has gone wrong with the 1990 convention. Specifically, we should consider the creation of a shorter list of universal “core rights” for migrant workers. This would have a higher chance of acceptance by a greater number of countries, thus increasing overall protection for migrant workers.

Exactly which rights should be on this shorter list is an important question to debate. In my view, the core rights should protect basic civil and labor rights, such as the right to keep your own identity documents, the right to equal access to the protections of the courts and the right to equal employment conditions.

But core rights do not need to include extensive social rights. Core rights should exclude, at least for a limited period of time, access to income-based benefits such as social housing and low-income support. In practice, these welfare benefits are already restricted under most labor immigration programs around the world.

An important caveat: The list of core rights should complement rather than replace the existing convention, which should continue to play an important role as an ideal toward which we should strive. Ideals and aspirational principles matter in global efforts to improve the lives of migrants.

In today’s world, what migrants need most are core rights that are protected now. It might be counterintuitive, but given the reality of labor immigration policy, when it comes to protecting migrant rights, less is more.