I personally believe that nobody has the right to kill another person, ever.
Putting aside my personal bias, I still believe Lights method of distributing "justice" was completely corrupt. It was ultimately him who decided who lived and who died. He killed people based on what he thought was evil. He only saw people as either lawful or corrupt, and killed them accordingly. In his world, the second you made a mistake you were disposed of. It's never a good idea to let someone have ultimate power, especially when they horribly abuse it.
Putting aside my personal bias, I still believe Lights method of distributing "justice" was completely corrupt. It was ultimately him who decided who lived and who died. He killed people based on what he thought was evil. He only saw people as either lawful or corrupt, and killed them accordingly. In his world, the second you made a mistake you were disposed of. It's never a good idea to let someone have ultimate power, especially when they horribly abuse it.