Evidence the computer records
Weapon the trasnporter
And you can convict without a body. And even you admit she likely broke the law. And it isn't about Tuvok and Neelix, it's about Tuvix a unique lifeform claiming his right to exist, a right which Janeway denied him.
I'm talking about evidence that Tuvix was a genuine life form rather than simply a transporter accident that Janeway fixed. Before they convict, they would have to agree that Tuvix was a sentient life form. What is the evidence for that?
Most of the jury would be swayed by two pieces of evidence. The testimony of Tuvok and Neelix and their own personal view on what constitutes sentience. Neither Tuvok and Neelix would say anything to support the claim that Tuvix was a true life form so it would be down to personal beliefs on sentience
I'm sure Janeway's lawyer would strongly play the...." Tuvix was a combination of two people"......card
How could you prove otherwise. Because he asked to live? As has already been discussed, that can easily be interpreted as many things including Tuvok or Neelix feeling a general sense of fear about proceedings and this fear manifesting itself in Tuvix as fearing for what he sees as his life
Lady Justice is often portrayed as being blind. So you are sitting on a Jury you don't know the people involved and you are shown computer records of Janeway terminating Tuvix's life how would you vote? It's immaterial that action brought back two others, if you take a life even if it saves others unless that person posed an immediate and life threatening danger to others you could still be charged with taking that life.
I would vote not guilty.
Specifically because I do not know how one measures sentience. Tuvix asking to live wouldn't be enough for me. In the end, I would probably find the concepts at hand, far too abstract and esoteric for me to fully engage with. I would look at the two people who made Tuvix possible and say, " they're still alive" so how can the material that made Tuvix, be considered dead when it's in front of me?
The only way I could see myself not feeling that way is if I believed that sentience was a spiritual, supernatural form in nature and was something that came from a none physical realm. But even then, it would be touch and go due to the monumentally complex nature of what was being asked of me