In the television series Star Trek, characters are often challenged with new and interesting ethical dilemmas. One of the best such challenges occurs during the episode “Tuvix” from the second season of Star Trek: Voyager.
In this particular episode, two characters are accidentally combined into a third character named Tuvix. Tuvix has many of the physical and mental qualities of the two characters he was made from. He even has some of their memories. However, he is a distinct person, with his own personality and desires. The show makes it clear that he is an individual and not just some vehicle containing and controlled by two other people.
The dilemma comes when the Voyager crew decide that they want to undo the process that turned two of their friends into Tuvix. This would mean bringing back their friends, but it would also mean destroying Tuvix in the process. Essentially, they would be killing him — something he explicitly points out to them in an attempt to convince them not to do it.
Generally when confronted with serious ethical problems, the characters on the show make decisions in accord with the libertarian ethics. In this case, however, they decided to murder Tuvix to bring back their friends.
There are, of course, scenarios where killing Tuvix actually would have been ethical. For example, if he had killed someone and, for whatever reason, killing Tuvix would bring is victim back to life, then killing Tuvix would be just fine from a libertarian perspective.
Furthermore, if Tuvix had been willing to die to bring back the original characters, then killing him would have been ethical as well.
Unfortunately, in this particular instance, the Voyager crew made the wrong decision and violated a rule even more important than the Starfleet Prime Directive: the non-aggression principle.