I live in Texas, and I supported capital punishment for a long time, but the more I learned about it, the more I came to oppose it. In the end, several factors changed my mind:
1. By far the most compelling is this: Sometimes the legal system gets it wrong. In the last 35 years in the U.S., 130 people have been released from death row because they were exonerated by DNA evidence. These are ALL people who were found guilty “beyond a reasonable doubt.” Unfortunately, DNA evidence is not available in most cases. So, as long as the death penalty is in place, you are pretty much GUARANTEED to occasionally execute an innocent person.
Really, that should be reason enough for most people to oppose it. If you need more, read on:
2. Cost: Because of higher pre-trial expenses, longer trials, jury sequestration, extra expenses associated with prosecuting & defending a DP case, and the appeals process (which is necessary - see reason #1), it costs taxpayers MUCH more to execute prisoners than to imprison them for life. This disparity becomes even greater when you consider the time value of money – most of the costs of capital punishment are up-front, occurring before and during the trial itself, whereas most of the costs of life imprisonment are spread over the term of incarceration (usually 30-40 years).
3. The deterrent effect is questionable at best. Violent crime rates are actually HIGHER in death penalty jurisdictions. This may seem counterintuitive, and there are many theories about why this is (Ted Bundy saw it as a challenge, so he chose Florida – the most active execution state at the time – to carry out his final murder spree). It is probably due, at least in part, to the high cost (see #2) - every extra dollar spent on capital punishment is one that's NOT going to police departments, drug treatment programs, education, and other government services that help prevent crime. Personally, I think it also has to do with the hypocrisy of taking a stand against murder…by killing people. The government fosters a culture of violence by saying, ‘do as I say, not as I do.’
4. It is inconsistently and arbitrarily applied. Factors that should be irrelevant (geography, race of the victim, poor representation, etc.) are all too often the determining factors in whether someone gets death versus life in prison.
5. There’s also an argument to be made that death is too good for the worst criminals. Let them wake up and go to bed every day of their lives in a prison cell, and think about the freedom they DON’T have, until they rot of old age. When Ted Bundy was finally arrested in 1978, he told the police officer, “I wish you had killed me.” Khalid Shaikh Mohammed (the architect of the 9/11 attacks) would love nothing better than to be put to death. In his words, "I have been looking to be a martyr [for a] long time."
6. Most governments are supposed to be secular, but for those who invoke Christian law in this debate, you can find arguments both for AND against the death penalty in the Bible. The New Testament (starring Jesus) is primarily ANTI-death penalty. For example, in the Sermon on the Mount, Jesus praises mercy (Matthew 5:7) and rejects “an eye for an eye” (Matthew 5:38-39). James 4:12 says that GOD is the only one who can take a life in the name of justice. In John 8:7, Jesus himself says, "let he who is without sin cast the first stone."