The Care Not Killing Alliance has turned down an invitation from Lord Falconer to give evidence to his Commission on Assisted Dying over concerns about its independence.

Care Not Killing leaders John Wiles and Peter Saunders said in a letter to Lord Falconer that the commission was “unnecessary, unbalanced and seriously lacking in transparency”.

They pointed to the fact that the commission had been launched at the suggestion of pro-euthanasia group Dignity in Dying and is being funded in part by one of its patrons, Terry Pratchett, an active campaigner for the legalisation of assisted dying for people with dementia.

The Care Not Killing leaders are concerned that most members of the Commission are already known to support the legalisation of assisted dying, among them Lord Falconer, Baroness Young, Baroness Murphy and Lord Blair.

The only disabled person on the panel, Dr Stephen Duckworth, has publicly spoken of his support for terminally ill adults to be given the right to opt for an assisted death.

“It is clear that the commission will have great difficulty being objective in its judgement,” said the letter.

Wiles and Saunders further argued that the failure of repeated attempts to legalise assisted dying and a comprehensive examination of the issue by a House of Lords Committee renders a new commission on assisted dying “unnecessary”.

In a separate letter to The Times this week, Saunders questioned the selection of the commission members.

“[The commission] is lacking in transparency as none of its members’ conflicting interests have been openly declared,” he wrote.

“Why is it, when the five major disability rights organisations in the UK (RADAR, UKDPC, NCIL, SCOPE, Not Dead Yet) all oppose a change in the law, that Falconer has chosen a disabled person who represents none of them and takes a contrary position?

“Why, when 95% of palliative medicine specialists and 65% of doctors support the status quo, has he picked four doctors who hold the minority view?

“Falconer’s grand jury is nothing other than a covert ploy to pull the wool over the eyes of politicians too busy to ask questions about its independence and objectivity.”

The commission was launched by Lord Falconer this month and will consider whether any changes to the law should be made to allow people the option of seeking assistance in dying. The inquiry is due to end in September 2011.