The effects of the death penalty are widespread and difficult to determine specifically. One problem with talking about the effects of the death penalty is that they vary across cultures and countries and may be different in specific cases or for specific crimes. In general, it is believed that the death penalty can discourage crime but that in many cases it fails to play a role in whether a crime is committed. There are many other consequences of the death penalty, including the emotional impact on executioners, the effect on prison populations when executions actually occur, and the varied fallout on families of executed criminals. In order to determine the effects of the death penalty, one must research the question as specifically as possible.
When most people think of the effects of the death penalty, the question that is really being asked is whether crime is being reduced overall. This question can be answered only in regard to specific areas and only for specific time periods. One factor that is known to make the death penalty more effective as a crime deterrent is the rate of executions, with fast and frequent executions reducing crime. Unfortunately, executing many people has other ethical and social effects as well, which may not be worth a superficial reduction in crime.
There are also other ways to think about the consequences of the death penalty. For example, living in an area where the death penalty is used to punish offenders makes people think about certain crimes differently. In areas where women can be put to death for adultery, attitudes about sex are logically informed by this type legislation. Given that each instantiation of the death penalty is necessarily different, the effects will always be different in each case.
Other ways of looking at this issue might include the ethical, social, and economic effects of the death penalty. The cost of the death penalty when compared to the cost of housing prisoners, for example, has an impact on the prison system overall. Philosophically, whether or not a nation has the right to put a person to death can affect areas of legislation as well. Socially, it is possible to look at whether the execution of a criminal family member has a positive or negative effect on the family, and the results often go either way.
Given the gravity of this type of punishment, the consequences of actually putting a prisoner to death are often different than the effects of the mere existence of the death penalty. Knowing that there is a death penalty, for example, is often enough to deter some people from committing a crime. Actually putting a prisoner to death affects everyone involved in the process psychologically, although not always in a negative way. There are many additional ramifications of the death penalty as well, and generalizations and statistics do not always reflect the actual experienced effects in any individual situation.