Withholding information from patients during an informed consent process is ethically unacceptable. Patients may restrict the amount of information they wish to receive or designate someone else to receive the information for them.
AMA J Ethics. 2015;17(3):209-214. doi:
10.1001/journalofethics.2015.17.3.ecas2-1503.
To participate in a lethal injection is to occupy the medical role and use medical training for a purpose that is not part of the goals of medicine and that harms the recipient of treatment.