You say capital punishment is ‘just’. What is ‘just’? Does that mean capital punishment can be used in all situations? Being ‘just’ has no meaning on its own. It requires a set of conditions within which justification can be seen.
It is true. The Church does not ban capital punishment completely. Instead, the Church teaches that capital punishment is permitted when
all other options are exhausted, and when there is an
imminent and actual threat to the safety of society. Those two conditions must be met before capital punishment can be used. Before you propose its use, you have to ask the question - will this execution protect against any further harm better than a life sentence?
In no way is it meant to be used for retribution. The Church does not see punishment as a form of retribution, but as rehabilitation. From the most solemn excommunication to the most minor penance, the objective of punishment is to reform and rehabilitate the sinner into good standing with God. Capital punishment is therefore a last-ditch resort to directly prevent further threat to life, where it is deemed more important than reforming the particular individual, like sniping a suicide bomber before he presses the trigger.
At the same time, some of you might have your priorities the wrong way round. You cannot rely upon capital punishments as a tool for controlling crime. Many countries have low crime rates not because they use capital punishment, but because they tackle crime at its source. Strong and efficient law enforcement and effective socioeconomic policies are necessary. Do not be afraid to give long jail terms, or to take decisive action against gangs, whether in the cities or in prisons.