is there a legal loophole for murder?

No, there is no legal loophole for murder. Murder is a serious crime in all jurisdictions and is punishable by law. It is not something that can be justified or excused through any legal loophole.

what about in self-defense?

Self-defense is a legal defense that can be used to justify killing someone in certain circumstances. It typically requires the individual to reasonably believe that their own life was in imminent danger and that the use of force was necessary to protect themselves. Each jurisdiction has its own laws regarding self-defense, so it is important to consult with a legal professional for specific guidance on this issue. However, it is important to note that self-defense is not considered a loophole for murder but rather a legal justification for taking a life in certain situations.