Leading judges rule today on a challenge brought by disability rights campaigners against the prosecution policy in assisted dying cases.
The campaigners accuse Director of Public Prosecutions (DPP) Alison Saunders of amending her policy in a flawed and "whimsical" way.
Nikki and Merv Kenward, supported by the Christian Legal Centre, say the change in wording makes the prosecution of healthcare professionals in assisted suicide cases ''less likely''.
The couple have asked three judges at the High Court in London to quash the amendment.
The Suicide Act 1961 makes it a criminal offence to assist or encourage suicide. The DPP has discretion on whether to prosecute according to the published policy.
Paul Diamond, appearing on behalf of the Kenwards at a recent hearing, argued that the amendment made last October represented a "substantive change" to the policy and made it more ''liberal'' - without the medical profession and other interested parties being properly consulted.
Mr Diamond referred to "the whimsical nature in which the policy has been amended" and the failure of the Attorney General to "superintend" the DPP on behalf of the Government.
Lawyers for both the DPP and the Attorney General have asked Sir Brian Leveson, Mr Justice Wilkie and Mr Justice Cranston, to dismiss the case, saying the amendment did not change but only "clarified" the policy and there was no need for a fresh consultation exercise.
Mrs Kenward, from Aston on Clun, Shropshire, is a former theatre manager confined by illness to a wheelchair.
She and her husband campaign against euthanasia and assisted suicide through the Distant Voices group.
She has said of the amendment: "If it is not removed, and this becomes the law, it will change how we view death. It will create a new means whereby euthanasia is an accepted form of behaviour."
But a man with locked-in syndrome who wishes to be able to end his own life has intervened in the legal action to back the DPP.
Referred to as "AM", or Martin, his lawyers argued the amendment to the policy was properly made and the application for judicial review should be refused.