Seven doctors from a leading private drug addiction clinic "failed in their duty" to their patients, a disciplinary hearing is told.
The seven doctors all used to work for the Stapleford Centre
The doctors are facing allegations of serious professional misconduct at the General Medical Council hearing.
The doctors, from London's Stapleford Centre, are accused of prescribing drugs inappropriately.
Andrew Collender for the GMC said they did not fulfil basic responsibilities. The doctors are still to put in a plea.
The case has been brought after one patient died after being sent home with a "DIY detox" kit.
The 29-year-old man choked on his own vomit in his sleep in September 2001 after taking the cocktail of drugs, including diazepam, rohypnol and temazepam.
It is thought to be the first time that so many doctors have been jointly charged.
Among those facing charges is Dr Colin Brewer, the founder of the clinic, which also has a site in Essex, for those addicted to heroin, alcohol and other drugs.
He faces charges in relation to the treatment of 13 of the 16 patients under consideration.
The remaining six doctors - some of whom no longer work at the clinic - are Anthony Haines, Hugh Kindness, Nicolette Mervitz, Martin O'Rawe, Ronald Tovey and Timothy Willocks.
It is believed the clinic was operating a policy of "maintenance" prescriptions in contrast to the NHS's tougher approach to weaning people off drugs.
At the opening of the hearing on Monday, Mr Collander said he accepted drug users presented particular challenges for doctors and there was a debate about what constitutes best care.
But he told the hearing there were still boundaries and added the case was about "the failure of these doctors to exercise care in certain specific respects".
He said a doctor must check an addicts medical condition and "degree of dependence and their tolerance before prescribing potentially lethal drugs".
The doctor should also choose treatment that would stabilise a patient's condition, "have a low potential for addiction itself, a low potential for injection and have a low street value".
He said the responsible practitioner should also be concerned with prescribing an appropriate combination of medication.
Mr Collender said the quantities prescribed should minimise the risk of overdose by a patient and people living with the patient, and cut the chance of diversion onto the streets for "profit or misuse".
And he said a "vital responsibility" was the monitoring of patients.
Mr Collender added the seven doctors did not fulfil "those basic responsibilities".
He also described the treatment one patient, known as RF, received at the clinic from 1990 to 2003.
The patient first went to the clinic in May 1990 when he was using heroin and 30 milligrams of methadone a day.
His initial prescription was for almost double that dose before gradually building up to nearly 400 mg of medication.
Mr Collender said: "The treatment he received turned a man at 23 with an unremarkable habit into one who at 13 years later was truly remarkable for the number of different drugs prescribed and the dosages of those drugs."
Speaking out in favour of the doctors, Andria Efthimion Mordaunt, of the campaign group John Mordaunt Trust, told BBC News 24 dealing with drug addiction was not easy or straightforward.
"I think it is a very important case. If they are struck off I think it will send a shot of fear through the entire prescribing community in this country."
The case was initially meant to be heard in February but had to be adjourned after Dr Brewer became seriously ill and could not attend the hearing.
The hearing, which is expected to last three months, continues.