Islam has protected humans from anything that can cause
harm and spread of sins. Some of what Islam has provided is
the law of Punishment that puts society in order and organize
people's relations in order to make them live in harmony. On of
the
important rules that the Islamic law was built on,is that a
person is not punished on behalf of another person's mistake.
The Punishment comes along with how bad the criminal act
was,so the robber wasn't punished by killing, nor the murderer
jailed for tow days for example, and then no Punishment was
build on suspicious doubts, unless solid evidence and eye
witnesses are provided. Islam made the Punishment of harming
society stronger. The drug dealers Punishment was not
mentioned in the Quran or sunna. But because of the great
damage caused to individuals and society, therefore the death
sentence is justified under special circumstances and comes by
the measurements of Islamic rules.