Back in 1972, the US Supreme Court outlawed the capital publishment statutes in all 50 states by a 5-4 decision in the case of Furman v. Georgia (408 U.S. 238 ).
All nine members of the court wrote separate decisions (!), so the exact legal reasoning behind the decision was less than crystal-clear. But broadly speaking, the decisions held that the death penalty could only be constitutional if applied in a consistent, non-arbitrary, and non-discriminatory way.
Almost a half-century later, what are the big-picture patterns of capital punishment in the United States? Tracy L. Snell at the US Bureau of Justice Statistics lays out the patterns in "Capital Punishment, 2018 – Statistical Tables" (September 2020, NCJ 254786). Here's the pattern of US executions over time:
One way of interpreting this graph was that the death penalty was on its way to being imposed only a very low levels in the 1960s, but after the nine-way Supreme Court decision eliminating all state capital punishment laws inflamed the issue, capital punishment then had a resurgence for a time, before fading again.
There are currently about 2600 prisoners under sentence of death. However, for some years now the number being removed from this category (usually by legal appeal or commutation of sentence rather than by execution) has been exceeding the number added.
Here's a figure showing the racial mix of those under sentence of death.
Strong opponents of the death penalty will of course feel that one execution is too many. But the Gallup poll suggests that at the national level, supporters of the death penalty continue to outnumber opponents. Moreover, at the state level there will be places with greater support or majority opposition to death penalty.
This report doesn't address policy questions about the death penalty, like whether it may at least in some cases deter murder. My own suspicion is that this question is that statistical methods probably cannot answer this question--but of course, the lack of a clear-cut statistical answer means that each of us will weigh the various risks involved in different ways. For a blog post on this topic from a few years back, see "The Death Penalty and Deterrence: Why No Clear Answers?" (June 25, 2012).
Timothy Taylor is an American economist. He is managing editor of the Journal of Economic Perspectives, a quarterly academic journal produced at Macalester College and published by the American Economic Association. Taylor received his Bachelor of Arts degree from Haverford College and a master's degree in economics from Stanford University. At Stanford, he was winner of the award for excellent teaching in a large class (more than 30 students) given by the Associated Students of Stanford University. At Minnesota, he was named a Distinguished Lecturer by the Department of Economics and voted Teacher of the Year by the master's degree students at the Hubert H. Humphrey Institute of Public Affairs. Taylor has been a guest speaker for groups of teachers of high school economics, visiting diplomats from eastern Europe, talk-radio shows, and community groups. From 1989 to 1997, Professor Taylor wrote an economics opinion column for the San Jose Mercury-News. He has published multiple lectures on economics through The Teaching Company. With Rudolph Penner and Isabel Sawhill, he is co-author of Updating America's Social Contract (2000), whose first chapter provided an early radical centrist perspective, "An Agenda for the Radical Middle". Taylor is also the author of The Instant Economist: Everything You Need to Know About How the Economy Works, published by the Penguin Group in 2012. The fourth edition of Taylor's Principles of Economics textbook was published by Textbook Media in 2017.