A man paralysed from the neck down is to find out later whether his doctors will be free from prosecution if they help him to die.
Tony Nicklinson, 58, from Melksham, Wiltshire, communicates by blinking and has described his life as a "living nightmare" since a stroke in 2005.
His High Court case goes further than past challenges to laws in England and Wales on assisted suicide and murder.
Any ruling is expected to be subject to an appeal.
'Misery'Father-of-two Mr Nicklinson was left paralysed with locked-in syndrome after a catastrophic stroke while on a business trip to Athens.
He was unable to attend court for the four-day hearing in June because of his complicated care needs.
In an email he said: "Legal arguments are fine but they should not forget that a life is affected by the decision they come to.
"A decision going against me condemns me to a 'life' of increasing misery."
The case differs from other "right-to-die" cases which have focused on assisted suicide. Mr Nicklinson would be unable to take lethal drugs, even if they were prepared by someone else.
For someone else to kill him would amount to murder.
In June, his barrister Paul Bowen QC told the High Court: "Tony has now had almost seven years to contemplate his situation.
"With the continuing benefits of 21st Century health and social care his life expectancy can be expected to be normal - another 20 years or more. He does not wish to live that life."
Mr Bowen added: "The claimant, who has made a voluntary, clear, settled and informed wish to end his own life with dignity, is too disabled to do so.
"The current law of assisted suicide and euthanasia operate to prevent him from adopting the only means by which he could practically end his life, namely with medical assistance."
'Untenable'David Perry QC, who is representing the Ministry of Justice, said Mr Nicklinson's "tragic and very distressing circumstances evoke the deepest sympathy".
Right-to-die cases
Diane Pretty was terminally ill with motor neurone disease. She wanted the courts to give her husband immunity from prosecution if he was to help her die. In November 2001 the House of Lords refused her application.
Ms B was left a tetraplegic by a brain condition. She went to court because doctors refused to stop her artificial ventilation. The High Court ruled in 2002 that her request was valid and treatment was stopped.
Mrs Z, who had an incurable degenerative disease, wanted to go to Switzerland to die and Mr Z arranged it. An injunction to prevent the travel was granted to the local authority. The order was overturned in 2004.
MS sufferer Debbie Purdy challenged the lack of clarity on the law on assisted suicide. She wanted to understand how prosecutors would make a decision on whether or not to prosecute her husband if he was to assist her to get to Switzerland to be helped to die. Ms Purdy won her case and guidance was issued.
"Notwithstanding the distressing facts of his situation, the defendant submits that the claim for declarations is untenable. The law is well established," he added.
The case is being contested on the issue of "necessity" arguing that the only way to end Mr Nicklinson's suffering is to allow him to die.
This was used in 2000 when conjoined twins were separated, saving one even though doctors knew the other would die.
Mr Nicklinson's team will also argue that his case is covered by Article 8 of the European Convention on Human Rights which deals with the right to respect for private and family life.
The judges will also publish a determination in the case of another paralysed man with locked-in syndrome, named only as Martin, who is 47.
Part of his case involves a challenge to the Director of Public Prosecution's policy on assisted suicide.
