Full Idea
The cause of death (injection or disease) is important from the legal point of view, but not morally. If euthanasia is desirable in a given case then the patient's death is not an evil, so the usual objections to killing do not apply.
Gist of Idea
If it is desirable that a given patient die, then moral objections to killing them do not apply
Source
James Rachels (No Moral Difference [1975], p.102)
Book Reference
'Ethics for Modern Life', ed/tr. Abelson,R./Friquegnon,M [St Martin's 1987], p.102
A Reaction
Seems reasonable, but a very consequentialist view. Is it good that small children should clean public toilets?