There are currently 65.3 million people worldwide who have been forced to leave their homes. That's the highest level of displacement ever seen, according to the United Nations Refugee Agency (UNHCR). The body is responsible for protecting the rights of refugees and asylum seekers around the world. And the bedrock of its work is the 1951 Convention relating to the Status of Refugees, which was adopted 65 years ago.

The landmark treaty defines who is a refugee and spells out the rights they're entitled to receive, as well as the responsibilities of states that grant them asylum. A refugee, it says, is someone who has "a well-founded fear of being persecuted for reasons of race, religion, nationality, (or) membership of a particular social group or political opinion," in their own country.

A key part of the treaty makes it clear that refugees have the right not to be sent back to a country where they face threats to their life or freedom.

Crucial treaty

The Refugee Convention was adopted at a special UN conference on July 28, 1951. It was initially limited to protecting the millions of Europeans uprooted by World War II, but was later opened up to all refugees with the 1967 Protocol.

"So it's a truly international human rights instrument… and an absolute foundational building block of international human rights law," UNHCR Chief Spokesman Adrian Edwards said in an interview with DW.

Over the past six decades, 142 countries have signed on to both the Convention and the Protocol. The commitment means they're obligated to protect refugees who flee to their territory, as well as provide aid, shelter, and access to education and work.

Syria, Afghanistan, Somalia

The bulk of today's refugees come from Syria, Iraq, Afghanistan and Somalia. According to the UNHCR, most of them have sought safety in developing countries fairly close to home.

Since the start of the war in Syria five years ago, more than 4.5 million Syrians have spilled over the border into neighboring Turkey, Lebanon, Iraq and Jordan. None of the latter three countries has ratified the 1951 Convention, meaning they technically have no obligation to recognize the displaced individuals as refugees. While Turkey has ratified the Convention, it maintains a "geographical limitation," which means it still only recognizes refugees from Europe.

"In the Turkish legal system there's no refugee status for non-European refugees," Hendrik Cremer, an expert on asylum at the German Institute for Human Rights in Berlin, told DW.

"It doesn't apply to other refugees, for example from Syria, Iraq, Afghanistan…According to the law, there's only weak protection against deportation for those refugees," Cremer added.

A number of Gulf states including Saudi Arabia, Kuwait, Bahrain, Qatar and the United Arab Emirates are also absent from the list of signatories. That's the case too for many countries in Southeast Asia like Malaysia and Thailand, which have been dealing with a wave of refugees from Myanmar's Rohingya minority.

Refuge in non-member states

A number of the Convention's principles, such as not sending someone back to a country where they face persecution, are also regarded as customary international law. Additionally, Edwards at the UNHCR says non-signatory countries in most cases still abide by refugee norms.

"Of course there are improvements needed in the legislative and practical arrangements for refugees, but for the most part, in most countries, refugees still manage to find asylum," he said.

Europe's refugee crisis

Refugees from Syria and other countries have also been arriving in record numbers in Europe, creating tensions between EU member states over how to handle the burden of new arrivals. The majority arrived by sea, while others trekked across a land route via Turkey. Most ended up in Germany, which registered more than 1 million asylum seekers in 2015. In an attempt to curb the influx, some countries closed their borders and introduced passport checks.

All European Union states are members of the Convention and Protocol, but Cremer has accused the bloc of failing to meet its obligations.

"Some countries have, because of nationalist, or you could even say very selfish reasons, resisted taking people in," he said. "Europe is gambling here with its credibility in the field of human rights."

Then there's the chaos caused by newer conflicts in countries like South Sudan. Recent clashes there have displaced 2.5 million people.

"This morning in Uganda, right on the border with South Sudan, we've been receiving people who have fled across the border from the recent upsurge in fighting," Edwards said.

The UNHCR is also on the ground in other African regions like the Lake Chad basin, northeastern Nigeria, Mali, Burundi and the Central African Republic, to make sure displaced people are receiving the rights they're entitled to under the Convention. Edwards says a severe shortage in funding means most of their work has become focused on life-saving aid rather than long-term assistance like getting children back in school and helping refugees find work.

Time for an upgrade?

The scale of the current global refugee crisis, combined with the changing reasons prompting people to seek refuge, has led critics to call for the Convention to be updated.

Questions have been raised over whether the document is still relevant, or whether the obligation of signatory states too great. On the other side, some complain the definition of a refugee is far too narrow at a time when scores of people have been displaced by a number of problems not just limited to persecution - from food insecurity in the Horn of Africa to gang violence Central America and climate change.

Although these realities aren't explicitly acknowledged in the text of the Convention, Edwards says it's "a flexible, adaptable instrument" that has saved millions of lives and is capable of taking on new meanings.

"Our view is this is something to build on, rather than seek to reconstruct," he said. "It's really essential that we have an international treaty like the Refugee Convention, and that that continues to be upheld, because frankly today the world needs it more than ever."

Anke Rasper contributed to this report.