Genesis 9:6 clearly teaches that if a man sheds another person's blood, then his life will be taken by the government. Moses wrote, "whoso sheddeth man's blood, by man shall his blood be shed: for in the image of God made he man." When a person premeditatedly takes a life, he not only assaults society but attacks God since man was made in His image. For those who accept the Bible as binding on what we believe and practice, that should settle the issue.
Advantage: justice, retribution, it's what the people want
Disadvantage: possibility of miscarriages of justice
Advantage: Justice, Safety, Law and Order
Disadvantage: Innocents could be wrongly accused, Not enough evidence to commit someone
Advantage: Deterrent to murderers
Disadvantage: Might kill innocent person
Advantage: Less murderers and rapists, You need more than that?, Taxes spent on things that deserve it
Disadvantage: Not a brilliant deterrent, Innocent people
Advantage: justice, retribution, it's what the people want
Disadvantage: possibility of miscarriages of justice
Advantage: Justice is served
Disadvantage: Murdering someone
Advantage: Clearing off dangerous individuals
Disadvantage: None as such, but I feel uneasy with the idea