Ethics are subjective, the law is clearly written and maintained.
For example some consider abortion unethical but abortion is legal in many places. So it is entirely possible to think someone acted in an (un)ethical way yet (dis)obyed the law.
MacLeod, the law is subjective as well. it's created by men, and sometimes it's wrong, too, and sometimes the ethical thing to do is to disobey it. And I'm not even thinking of the abortion debate--that was never in my head as I've been posting here, although I recognize that many others bring these bags of preconceptions to the table. It's also entirely possible to obey the law to the letter and do the wrong thing, ethically. The fact that a law is written on paper changes nothing. It was illegal in slave states in the US to hide runaway slaves. What was the ethical thing to do?
But in this case, the truth is we don't even have the law to guide us. Do we have any idea of what Federation law is on this subject? How is it we can even begin to apply 21st century jurisprudence to this situation? Janeway and her officers were in uncharted legal territory--even for the Federation. So the best we can do is to fall back on our ethical/moral compasses, so to speak. That's all we can do. And my conclusion, always, in every single post in this thread, was that killing Tuvix is murder, and leaving Tuvok and Neelix "mostly dead" is murder as well, if they're forever left in that state of non-being.