Some jurisdictions do allow the condemned to choose, typically between lethal injection and electrocution; a few states allow the choice of hanging as well. Utah allows firing squads for inmates sentenced prior to 2004, and executed Ronnie Lee Gardner by that method last June.
I once had a conversation with the warden at the Texas prison unit where executions are performed; he told me that executions are performed by a privately contracted outside party whose identities are kept secret and involves no medical personnel (i.e. doctors and nurses). In most states they’re phlebotimists and/or EMTs.
That surprises me, as that would contradict the oath taken by EMTs and Code of Ethics of the American Society for Clinical Laboratory Science, which governs phlebotomists.
I’d prefer OD or something even more noble.
When talking about lethal injection, isn’t a more important distinction the fact that an artery will carry the poison to only one part of the body, while a vein will carry the poison directly to the heart, and from there it will go everywhere in the body?
I’m sure you know much more about the subject than I do. Maybe I’m getting it wrong.
addendum - actually, I see you addressed my point in post#2.
We’re killing them! Is their dignity REALLY important?
Yes.
Arterial blood is at a different PH to veinous blood, many drugs that are given IV will immediately crystalize in an artery… very unpleasant. However if there where no periferal veins to be had it would be fairly simple to cannulate a major vein in the neck such as internal/external jugular.
Paging QtM! Paging QtM!
I don’t want to say bullshit since IANAMD, but the blood is just going around in a circle. Why would the pH be different in an artery than a vein??
Because arterial blood is loaded with oxygen and lower in CO2, and venous blood is depleted of the former and has more of the latter. This does change blood chemistry in significant ways. Venous blood is less basic. If arterial blood pH is 7.35, the the venous blood is likely around 7.3 or so.
Few drugs are designed to be delivered intra-arterially, but I doubt many of them would be all that affected by the pH difference.
The whole argument for execution by arterial infusion is rather Rube Goldbergesque anyway. There are many simpler, more effective ways to do someone in.
I don’t know what Paging QtM means but I’m guessing it’s an attempt at sarcasm still… (ah…I was wrong)
Because arterial blood isn’t carrying all the waste products of metabolism…
I’m crushed! Crushed, I tell you! 
Actually it’s carrying quite a bit of it, specifically to the kidneys and liver, where many such waste products will be removed. Not many waste products, besides CO2, leave the body via the lungs in significant amounts.
Isn’t it the co2 from metabolism that changes the PH?
I’m a licensed EMT and I don’t remember seeing that oath in my initial training, it certainly wasn’t covered in any way during my re-cert, and I would be amazed if it were in any way legally binding even if I did sign or otherwise acknowledge it during my initial training.
Actually, having just read the oath, I am sure I never signed it. I would have outright refused to sign any document that forced me to (implicitly at least) accept the existence of God.
Yes, it is.
Regardless of this, arterial blood carries lots of other waste products, and only somewhat less CO2 than venous blood does.