You're right. Your "crimes", my "crimes", and criminals crimes have already been punished and paid for, so forcing payment again is unjust - it is double jeopardy.
precludes arrest and trial for any crimes, and probably even precludes self-defense.
Au contraire mon FR-ami. It is the duty of government to protect the life, liberty and free pursuits of individuals and to keep society safe from without and within. So there should be due process in dealing with the accused, but the sentence for criminals found guilty of heinous crimes and deemed dangerous to others should be incarceration, not for punishment, but for the protection of society.
The most effective way to protect society is to remove the offenders.
Permanently.
Your argument simply doesn't work.