A lawyer who advised doctors that they must let a 22-year-old Jehovah's Witness die even though he wanted to live has spoken of the agonising scenes before the young man's death.

Robert Tobin, a partner in the London law firm Kennedy’s, was called in by an unnamed NHS Trust when the man, a Jehovah’s Witness who was critically ill with sickle cell anaemia, refused a blood transfusion which could have saved his life.

Over three weeks the man gradually deteriorated as the crisis progressed, before eventually dying.

“Medical staff were understandably upset at seeing a patient deteriorate before their eyes knowing a simple procedure could have been provided that would have saved his life,” Mr Tobin said.

The man’s mother, also a Jehovah’s Witness, was at her son’s bedside, and an elder from the man’s church also attended. The trust was concerned that they were unduly influencing him but a doctor from a neighbouring trust who was called in to assess him said he had full capacity and was making the decision on his own.

Mr Tobin said: “I don’t know what his mother was thinking as she sat by and watched him die. I assume either she felt powerless or she felt bound to her own religious code of conduct which says you can’t share blood with others.

“He had full capacity, he made his decision, however irrational. His doctors were bound by that. The rules are very clear.”

Mr Tobin said that at the Trust’s request, the Jehovah’s Witness signed an advance directive - the so-called “living Will” - setting out his wishes in case he lost mental capacity in the future.

Mr Tobin highlighted the ethical discrepancy in the law which forbids the same doctors from assisting those who want to die.

He contrasted the Jehovah's Witness's case with those cases raised in the debate over assisted dying, in which patients have petitioned the courts for the right to seek help to end their lives.

Last week Tony Nicklinson who has “locked in” syndrome after suffering a massive stroke, sought a ruling exempting doctors from criminal prosecution if they assisted his suicide.

“There is a subtle distinciton between a patient’s right to life and a patient’s right to die,” Mr Tobin said.

While the law forced medical staff to stand aside and not intervene in the case of the 22 year old Jehovah’s Witness, even though the man had no intention of ending his life, they were prevented from intervening to help patients such as Tony Nicklinson die at a time of their choosing.

“But the same doctors could be faced on a another day with a patient who wants assistance to die when his condition becomes impossible to live with. In that case the doctors could face criminal prosecution if they helped him to realise his wish,” said Mr Tobin.

While the legal distinction was clear for doctors treating the Jehovah's Witness, the ethical one was not. Both patients wanted to exercise their personal autonomy but only one - the Jehovah’s Witness - was able to do so, because he needed no assistance.