Introduction with your thesis statement Although some may object to the death penalty, this punishment is necessary to control public order and to ensure people's safety.
Body: your actual argument
1. First of all, the death penalty is necessary to control public order
2. Secondly, the death penalty is necessary to ensure people's safety
3. However, the death penalty, when executed to quickly, may inadvertently kill the wrong culprit.
Conclusion (All in all, to conclude, in conclusion)