The deaths of Craig Ewert and Daniel James are bound to reignite a heated debate over euthanasia and assisted suicide.

Although suicide is no longer a crime in England and Wales, aiding and abetting suicide is a criminal offence punishable by up to 14 years in prison.

Veteran MSP Margo MacDonald who has Parkinson's Disease has also launched a campaign to make assisted suicide legal in Scotland.

The calls for a change in the law have been marked by high-profile legal bids and a steady stream of publicity about UK citizens who have travelled to Dignitas, the Swiss clinic, to die.

Dignitas was founded in 1998 and takes advantage of Switzerland's liberal laws on assisted suicide which suggest that a person can be prosecuted only if they are acting out of self interest.

The issue was brought to widespread attention in 2002 when Diane Pretty, 43, a terminally ill woman, launched a legal bid for her husband to be allowed to help her take her life without fear of prosecution.

She died at a hospice in May that year near her home in Luton, Bedfordshire, shortly after losing her case in the European Court of Human Rights.

Her lawyers had argued that under the European Convention on Human Rights, which guarantees the right to respect for private life and bans inhuman and degrading treatment, she should be allowed to die with dignity, rather than face the distressing final stages of her disease.

In 2006 an Assisted Dying Bill, brought by retired human rights lawyer Joel Joffe, was rejected in the House of Lords.

His bid was followed by a legal challenge this year by multiple sclerosis sufferer Debbie Purdy, 45, from Bradford, West Yorkshire, to clarify the law on assisted suicide.

Ms Purdy, who is wheelchair bound, had gone to the High Court in a bid to force the Director of Public Prosecutions to issue specific policy guidelines.

She wanted to know if her husband, Omar Puente, the Cuban violinist, could help her travel to Dignitas if her illness became too much to bear, without fear of prosecution.

She lost her legal bid but the case prompted some commentators to warn that, if successful, her bid could have resulted in a much tougher approach to assisted suicides.

They have pointed out that although a handful have been arrested, no relative or friend of the more than 100 UK citizens who have gone abroad to Dignitas clinics has been prosecuted under the 1961 Suicide Act.

These families include that of 66-year-old Dr Anne Turner, from Combe Down, Bath, who took her life with the help of doctors at the Dignitas clinic in 2006.

She had been suffering from progressive supranuclear palsy, an incurable brain disease and died surrounded by her three children after drinking a lethal dose of barbiturates.

Other cases include Reg Crew, 74, from Liverpool, a motor neurone disease sufferer, who travelled to Dignitas to die in 2003 accompanied by his wife, and Robert and Jennifer Stokes, of Leighton Buzzard, Beds, who died at Dignitas in 2003. An inquest into their death in 2004 heard they had both suffered a range of mental and physical illness over a 30-year period but were not terminally ill.

Alayne Buckley, 61, of Wakefield, West Yorkshire, who had motor neurone disease, died at Dignitas in 2005 accompanied by her husband Derek, and Valere Sliwinski, 58, of Clacton-on-Sea, Essex, who had cancer and multiple sclerosis, died at the clinic in 2006.