Does the Death Penalty Deter Crime?

Ben Tyree PLSC 374 Dr. Wang 7 December 2005

The Theory of Deterrence

• “This theory rests upon the belief that nothing is so sacred to an individual as his life. The prospect of impending death is a threat too ominous to be ignored. While one might be willing to run the risk of a lesser penalty for the sake of achieving his object, he would not be willing to risk anything so highly cherished as life itself. The death penalty, therefore, is upheld as the most powerful of all deterrents, and a potent aid in the repression of crime.” 1 1 Bye, Raymond T. Capital Punishment in the United States. Menasha, WI: George Banta Co., 1919. 31-40.

Hypotheses

 1) States with a death penalty statute will have lower rates of crimes punishable by death than states without death penalty statutes.

 2) States that have the most executions will experience fewer crimes punishable by death than states that do not use their death penalty often and those without a statute at all.

To Execute or Not?

• Death penalty statutes exist in 38 states.

• These states do NOT have the death penalty: Alaska, Hawaii, Iowa, Maine, Massachusetts, Michigan, Minnesota, North Dakota, Rhode Island, Vermont, West Virginia, and Wisconsin

Murders in the U.S., 1970-2004

23440 23040

24000

21610 20510 18980

21000

15586 16137

18000

16000

15000 12000 9000 6000 3000 1970 1975 1980 1985

year

1990 1995 2000 2005

100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5

U.S. Executions Per Year 1976-2004

98 85 74 68 1 2 1 2 31 5 25 21 18 16 11 23 14 38 31 56 45 66 71 65 59 year

What Crimes are Punishable by Death?

• All states with the death penalty hold that first-degree murder is a crime punishable by death • Some states consider other crimes also punishable by execution: – Treason, train wrecking, perjury causing execution, capital drug trafficking, capital sexual battery, kidnapping with bodily injury or ransom when the victim dies, hijacking an aircraft, aggravated rape

Testing Hypothesis 1 Case Study One

 States with a death penalty statute will have lower rates of crimes punishable by death than states without death penalty statutes.

• Texas has executed far more people than any other state (336/944), so according to hypothesis 1, Texas should have a lower crime rate than a state without a death penalty statute, such as Michigan.

18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Crime Rates 1970-2000: TX vs. MI

(murders per 100,000 inhabitants) 11.6

9.4

13.4

11.9

16.9

10.2

13 11.2

14.1

10.4

6.7

5.9

Texas Michigan

1970 1975 1980 1985 1990 1995 2000

Significance of TX vs. MI

Death Penalty?

Pearson Correlation Crime Rates .391

Sig. (2-tailed) .166

NOT STATISTICALLY SIGNIFICANT!

N 14

Testing Hypothesis 1 Case Study Two

 States with a death penalty statute will have lower rates of crimes punishable by death than states without death penalty statutes.

• Virginia was second behind Texas in number of executions from 1976-2004 (94/944). Again following hypothesis 1, Virginia should have a lower crime rate than Massachusetts, which does not use the death penalty.

13 12 11 10 9 3 2 1 0 8 7 6 5 4

Crime Rates 1970-2000: VA vs. MA

(murders per 100,000 inhabitants) 11.5

10.4

3.5

4.2

8.6

4.1

7.1

3.5

8.8

4 7.6

3.6

5.7

2 Virginia Massachusetts

1970 1975 1980 1985 1990 1995 2000 Year

Significance of VA vs. MA

Death Penalty?

Pearson Correlation Sig. (2-tailed) Crime Rates .874** .000

STATISTICALLY SIGNIFICANT!

N 14

**Correlation is significant at the 0.01 level (2-tailed).

The correlation is significant, but not in the direction hypothesized.

Comparing Crime Rate Means of States currently with and without the Death Penalty in 1970 and 2000

• 1970 (still moratorium on death penalty) – States

without

current death penalty • Mean murders per 100,000 inhabitants:

3.9417

– States

with

current death penalty • Mean murders per 100,000 inhabitants:

7.8395

• In 1970, states that currently have a death penalty statute had nearly twice the murder rate as those who do not currently have the death penalty – Suggests justification for those states to reinstate the penalty after moratorium was lifted in 1976 • 2000 (moratorium lifted 24 years before) – States

without

current death penalty • Mean murders per 100,000 inhabitants:

2.8250

– States

with

current death penalty • Mean murders per 100,000 inhabitants:

5.3789

Comparing Crime Rate Means of States currently with and without the Death Penalty in 1970 and 2000 (continued)

• Differences of 30 years • The 2000 mean murder rate of states that do not have the death penalty is 71.7% of the 1970 rate • The 2000 mean murder rate of states that do have the death penalty is 68.4% of the 1970 rate • States that instituted the death penalty experienced a 3.3% larger drop in murder rates than states that did not institute the death penalty • Sig. (2-tailed)=.192

– Not significant

Testing Hypothesis 2 Case Study One

 States that have the most executions will experience fewer crimes punishable by death than states that do not use their death penalty often and those without a statute at all.

• Missouri executed 61 convicts between 1976 and 2004. Montana executed 2. Therefore, although both have death penalty statutes, Missouri should have a lower rate of murders.

Crime Rates 1976-2000: MO vs. MT

(murders per 100,000 inhabitants)

12 11 4 3 2 1 0 10 9 8 7 6 5

Missouri Montana

19 76 19 79 19 82 19 85 19 88 Years 19 91 19 94 19 97 20 00

Significance of MO vs. MT

Crime Rates Death Penalty?

Pearson Correlation .903** Sig. (2-tailed) .000

STATISTICALLY SIGNIFICANT!

N 14

**Correlation is significant at the 0.01 level (2-tailed).

The correlation is significant, but not in the direction hypothesized.

Testing Hypothesis 2 Case Study Two

 States that have the most executions will experience fewer crimes punishable by death than states that do not use their death penalty often and those without a statute at all.

• Oklahoma executed 75 convicts between 1976 2004. Pennsylvania executed 3. Hypothesis 2 contends that Oklahoma will have a lower crime rate than Pennsylvania.

Crime Rates 1976-2004: OK vs. PA

(murders per 100,000 inhabitants)

13 12 11 10 9 8 7 6 5 4 3 2 1 0

Oklahoma Pennsylvania

19 76 19 78 19 80 19 82 19 84 19 86 19 88 19 90 19 92 19 94 19 96 19 98 20 00 Year

Significance of OK vs. PA

Crime Rates Death Penalty?

Pearson Correlation .667** Sig. (2-tailed) .000

STATISTICALLY SIGNIFICANT!

N 14

**Correlation is significant at the 0.01 level (2-tailed).

The correlation is significant, but not in the direction hypothesized.

Comparing 2004 Crime Rate Means of States that Often Execute Convicts and States that Do Not

• Frequent usage defined as at least one execution per year (≥29) • Nine states fall into this category • Mean 2004 Crime Rates for states that frequently use the death penalty: 6.32 murders per 100,000 inhabitants • Mean 2004 Crime Rates for states that do not frequently use the death penalty: 4.08 murders per 100,000 inhabitants • Sig. (2-tailed)=.135 (NOT significant)

Conclusion

• • • •

Both the Texas/Michigan test and the Virginia/Massachusetts test REJECTED hypothesis 1.

Comparing the crime rate means of all states currently with and without the death penalty in 1970 (under moratorium) and 2000 confirmed the results of the first two tests.

Both the Missouri/Michigan test and the Oklahoma/Pennsylvania test REJECTED hypothesis 2.

States that use the death penalty, on average, once per year, do not have lower murder rates than those who do not use the death penalty often or not at all.

Future Research

• David P. Phillips introduces the idea that capital punishment may be a deterrent to crime, but only in the very short term. Rather than analyzing years, Phillips looked at crime rates in England on a weekly basis for a 53-year period. He found that the week after an execution usually had a lower crime rate. This would be an interesting, but tedious, study to conduct with a wider geographical sample and with more recent statistics.