Ahmed, 17, knows exactly how long he's been in the Jungle refugee camp in Calais: two months and 15 days. He comes from Damascus in Syria and traveled to Europe with a friend, also 17. Now they're risking their lives to get to England.

He's staying in a small, blue tent, with two others. Ahmed lost all his family in Syria and doesn't know what happened to them — maybe they were killed, maybe detained. There's only one family member left for him: his brother, a 21-year-old who is living in London.

The teenager tries to get on trucks or trains three or four times a week. "I was in a truck before but when the police caught me they put gas in my face and hit me with a stick," he told VICE News.

He wants to go to school and study to become a car mechanic. "I just need to live with my brother because I have no other family," he said. "If my brother was in France I would stay in France. If my brother was in Belgium I would stay in Belgium."

Nervous and sad, Ahmed kept his eyes fixed on the ground as he recounted his story. "It's too bad, too cold [here]," he said. "I'm scared about this place with everyone in it because I am alone with no family. My friends might leave some day and leave me alone here."

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It's not difficult to find children in the Jungle refugee camp in Calais, France, where around 5,000 migrants are currently living in muddy and depressing conditions, around 20 miles from the coast of Britain.

Ahmed is just one of around 200 minors there who have been identified as having direct relatives in the UK. On Monday, they became the new battleground in UK immigration law, as a challenge to their situation began in a court in central London.

A little-known clause in the Dublin III Regulation, which covers European Union (EU) asylum policy, says unaccompanied minors with close family members who are legally resident in another European country should be allowed to be reunited with them. However, activists argue that Britain has not effectively implemented this clause, as minors still need to travel onto UK soil to make their asylum application.

The new case will decide whether four young Syrians in the Calais Jungle can be reunited with their families in the UK, after their attempts to have Britain take over their asylum applications were rejected by the Home Office.

Before the first day of hearings began, VICE News spoke to the brother of one of the applicants, a 15-year-old currently in the Jungle.

The two were born in Daraa in Syria. They left the war-torn country separately: the older brother escaped first, accompanied by his wife. The siblings' parents then encouraged the 15-year-old to follow him.

"During the journey my brother would just be using other people's phones in order to contact me, so there were long periods of time where I couldn't contact him," Hassan — whose name has been changed for legal reasons — told VICE News. "I only managed to be in frequent contact with him when he reached France."

Hassan came through Calais himself — he arrived in the UK in a refrigerated truck. He can't travel to France again until he gets a travel document, so their communication is just by phone.

"Mentally my brother is distraught because he's growing very impatient remaining in Calais because the conditions are so bad and I'm growing very frustrated because there is no way for me to see him. We're just trying to calm him down and reassure him that this might work, we can be reunited."

Hassan also said the teenager would have suffered had he stayed in Syria. "If my brother remained there there's currently army conscription going on, and they're targeting the younger people so if he stayed he would have been forcibly taken. He couldn't have gone to school. His life would have been really disrupted... Alternatively, he could have been approached by armed groups like Daesh (Islamic State) or al Nusra who would have convinced him to join them."

In the meantime, his brother endeavors to board trucks and trains, even though it's highly dangerous. "My brother keeps trying, he's tried a few times to get here but he hasn't been successful."

"It's very difficult to explain and express how frustrated I feel because it's very frustrating to know that a member of your family is an hour away, a train ride away, and that you can't see him and he can't come here. It just feels like a very desperate situation."

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More than one young person stuck a mere 50 miles from their closest family members hasn't lived to see this legal challenge, however.

Also on Monday, a memorial service was held in St. Andrew Holborn church, central London, for Masud, a 15-year-old from Mazar-e-Sharif in Afghanistan. He was suffocated to death a few weeks in the back of a truck in Dunkirk, France, and had also been living in the Jungle camp.

Shortly after his body was discovered, Mohammad, the refugee who shared a tent with Masud, told VICE News that the boy had set off from Calais to Dunkirk in the hope of finding another way to reach England and his sister.

"Many refugees are putting their lives in danger to cross to the UK," he said. "I hope for a big political change of polices of migrants so we don't lose these precious lives any more."

Representatives from three different faiths — Islam, Judaism, and Christianity — made speeches at the memorial on Monday, along with activists and others who had visited the French camp.

Mourners at a memorial service held in London for Masud, an Afghan 15-year-old who died trying to reach his sister in the UK. (Photo by Sally Hayden/VICE News)

Speaking at the service, jazz musician Ian Shaw said he once drank tea with the teenager. "I had the pleasure of meeting Masud," Shaw said. "He was proud, determined, very funny."

Bishop Peter Hill called for a change in Britain's immigration policy. "It is unacceptable that our government remains inactive on this," he said. "What if this was your child? As a Christian leader in what is at least officially a Christian nation, we know that Jesus did not turn children away."

After the memorial, attendees laid white flowers in memory of Masud and others that had died attempting the same journey. George Gabriel from Citizens UK thanked the people who attended, saying he had spoken to Masud's brother-in-law that morning. He said the family were dealing with "crushing grief." They are now trying to work out how to fly Masud's body back to Afghanistan.

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Apart from the grim conditions inside the camp and the risk of injury or death trying to escape it, there are other reasons a minor might be at risk in the Jungle.

British volunteer Rick Melling leads the distribution of clothes and other provisions for French NGO L'Auberge des Migrants. At the camp, he told VICE News that, besides the "mental health issues and desperation" that can be a consequence of living with so little hope, teenagers in the Jungle are also at risk of being recruited by people smugglers or other groups. They would then be forced to do tasks like opening car doors while people climb in.

Melling said he comes across minors very often. "It's a case quite a lot of the time that a 12-15 year old lad has lost all of his family... Getting to the UK is the last chance that he's got."

It only took VICE News an hour in the Jungle to run into someone whose life could be changed by a potential ruling in Britain. Walking down a dirt path, hood pulled tight around his ears, was 16-year-old Omar, from Eritrea.

Omar has been in the Jungle for two months. He has a brother and sister in Manchester and is currently sharing a small, square, wooden shelter with seven other Eritreans. He said he tries to get to England nightly, but is always unsuccessful. He also claimed he has been punched in the face by the French police and tear-gassed. Holding out his broken phone, Omar said the police had grabbed it from him and smashed it on the ground. He said one policeman had stamped on his feet.

It's been a year since Omar left Eritrea. He walked for weeks through the deadly Sahara desert, was imprisoned and tortured in Libya, and has reached a stage where he's willing to risk everything to finally reach his family.

Though he spends the majority of his time focused on survival, Omar still has dreams. He said he wants to study and go to university, and one day be a doctor. He said it's dangerous for him to stay in the camp.

VICE News heard of other many cases, including that of a 15-year-old who got separated from his mother on the boat journey between Turkey and Greece. His mother now has a UK passport. She comes to visit him in Calais when she can, though she also has a young baby to look after.

While in the Jungle, VICE News also met Laura Griffiths who runs the minors screening process for Citizens UK. Since October she's been identifying under-18s throughout the camp.

"The law is there and the legal process isn't working and this is the government's failure to put that in place — the consequence of which is children jumping onto trains, jumping in [trucks], suffocating in [trucks] trying to reach their family in the UK."

Griffiths said separations happen for different reasons. "Some of them get lost en route... Some of it is what families can afford."

She said she'd like to see the British government "take their responsibility under Dublin III as they should, [and] implement it effectively and efficiently."

Griffiths added: "It's difficult for everyone living here. The conditions are dire and there's not adequate care for children here... So it's just awful. No human being should be in this condition and no child should be in this condition."