In the entrance hall of a run-down block of flats, a group of teenagers stood hanging out, smoking, track-suit hoods up, shoulders hunched, seemingly nonplussed that they were getting drenched. A storm was blowing rain into the building on the Chêne Pointu estate. There was no front door to keep it out. Nor were there any lobby windows – just buckled metal and a few shards of smashed-out glass surrounded by graffiti saying "Fuck the police". The mailboxes were mostly broken, but anyway there weren't enough of them for all the people crammed into the block, some sharing rooms in flats run by slum landlords.

The lift hadn't worked for six years and residents who couldn't drag their shopping up the unlit stairwell had to rely on young "porters". Some rigged up pulley systems to hoist shopping to their windows, where the glass was cracked and fixed with tape. Some apartments had walls black with mould. Last year there were 20 tuberculosis cases here.

"Even in the third world it's not like this," said Merzuk, 35, who works in a local photocopy shop. "This is a world apart."

Described by a Socialist politician as "France's most run-down estate", La Chêne Pointu has a special place in France's psyche. It was here in Clichy-sous-Bois in 2005 that the deaths of two boys who had been running from police were the catalyst for the worst riots in modern French history. Three weeks of uprisings spread through high-rise estates across France, with more than 9,000 cars torched and dozens of public buildings trashed. The government declared a state of national emergency.

In the wake of that crisis, it seemed that the high-rise ghettoes of France's neglected banlieues would have to change forever. But last week, the latest twist in a seven-year fight by the boys' families for justice revealed how little has really changed. At La Chêne Pointu, where more than 70% of the 6,000 residents live under the poverty line, the mood remains grim.

There has been no trial over the deaths of Zyed Benna, 17, and Bouna Traoré, 15, who were electrocuted while hiding from police in a sub- station. Last week France's highest court overturned a ruling that the case be dropped. Two police officers could now face trial for failing to come to the boys' aid.

"It is terrible it has taken seven years to get a possibility of justice," said Sana Abdelhafidh, 27, a childminder who was born on the estate. "But nothing's going to change here – if anything, things have just got worse. There's a semblance of new construction work, but fundamentally it is still the same."

If a trial is ordered, it could plunge to the heart of a central problem still plaguing French society, and which has been the trigger for more recent riots from Clermont-Ferrand in central France to Amiens in the Somme: the dire relationship between police and young people, particularly non-white young men and teenagers. While unemployment, poor housing, daily discrimination and racism have run local people into the ground in the poorest parts of Clichy-sous-Bois, it is the daily conflict with police that remains a tinderbox.

At the centre of the Zyed and Bouna deaths is the continuing issue of police controls, stop and searches and identity checks. This year more than 20 citizens sued the government over alleged racist policing, claiming that they were stopped by police purely because of the colour of their skin.

In January the US-based Human Rights Watch accused French police of carrying out identity checks based on race. A study by the CNRS research institute showed that people of Arab appearance were eight times more likely to be stopped than white people, and black people six times more likely.

Police unions denied outright that racism was at play in what campaigners say are continual, arbitrary and at times insulting and aggressive stops made on housing estates, or at Paris locations like the Gare du Nord, or in "white" places such as around the Eiffel tower, where, they say, black people are stopped and asked what they are doing.

Non-white teenagers in certain areas complain of being frisked on their way home from school. While for years the tense relationship with police was blamed on the hardline policies of rightwing Nicolas Sarkozy, the Socialist François Hollande is now under pressure to act.

Sarkozy promised during his campaign that the "discrimination" of constant stop and searches against non-white people merely walking down the street would stop. But the government is divided over a promise to issue receipts after police checks, and better monitoring of policing.

Sihame Assbague, a spokeswoman for the lobby group Stop Le Contrôle au Faciès, said the Zyed and Bouna deaths "have marked a whole generation in France because it could have happened to any of us". In October 2005, during half-term, the boys had gone for a football match and were coming home for the evening Ramadan meal. When a police van crossed their path, they ran, although an inquiry established that they had done nothing wrong. The families' lawyers pointed to the "absurdity" of kids running just because of the police, and police chasing just because they were running. The two boys hid in an electricity sub- station and were killed by tens of thousands of volts.

Mohamed Mechmeche, a community worker who after the riots founded the community pressure group AcLefeu, said: "This struggle for justice is not against the police; it is about them taking the stand and saying what happened. If they are acquitted, it is important to be acquitted before a court. It has been hard to convince young people to move beyond that tense relationship with police when they thought there was a sense of impunity, no justice."

Mechmeche, like others on the estate, feel there has been no fundamental change here since the riots. If anything, the economic crisis had made the scourge of unemployment even worse – on estates such as La Chêne Pointu, where more than half the population is under 25, joblessness tops 40%. Young French people here still say their address, skin colour and "non-French-sounding names" mean that their CVs are thrown in the bin.

Despite new building work and the town's first ever police station – which is so grandiose it looks like an opera house – there is still no unemployment office. The state has a plan to renovate the privately owned Chêne Pointu estate, but it could take years. It is only 15km to Paris, but there is still no direct transport route from the capital.

A few miles north, in his council flat in the high-rise estates of Villiers-le- Bel, Mara Kanté explains why the notion of justice for Zyed and Bouna is so important across France. In 2007, riots broke out in Villiers-le-Bel after two teenagers were killed when a motorbike they were riding collided with a police car.

It was the first time firearms were widely used against police, with around 90 officers wounded. Kanté, a local football star who had trials in England and played no role in the attacks on police, was held in prison for 29 months, 11 of them in solitary confinement, accused of attempting to murder officers. He was cleared on appeal after a controversial trial before which the police had offered cash rewards and anonymity in exchange for witness statements.

"I am not the only one who's been through something like this; lots of people have," he said. "It is just that I fought hard to speak out about it. There is a justice system with several speeds depending on your social class.

"It is still very tense between young people and police here. This place has been sacrificed, cast aside. Police checks here now are constant, more aggressive, less human. There is a pseudo-politeness to them which is like putting a tiny bit of sticking plaster over a big open scar. Society still seems totally divided."