waran said:Classically the Hippocratic oath forbids it exclusively.
Hence why they developed a special "euthanasia" machine where a nurse hooks you up to an IV, then you are asked 3 times by the computer "Are you sure?". A doctor cannot (and I would imagine a nurse will not) intentionally deliver a lethal dose of anything. In the lethal injection the nurse just hooks up the condemned, they do not inject the chemicals.
Just as an aside while I have "euthanasia" in my mind: did you know that the word "suicide" is not allowed on BBC factual programmes? This is why on the news they will always say things such as "Took his own life" but never "suicide".