Most crimes are not irrational acts. Instead, they are committed by people who at least implicitly compare the expected benefits with the expected costs, including the costs of being caught and punished. The reason we have so much crime is that, for many people, the benefits outweigh the costs — making crime more attractive than other career options.

"The criminal justice system constructs a list of 'prices' (expected punishment) for various criminal acts."

It is virtually impossible to prevent people from committing crimes. What the criminal justice system does is construct a list of “prices” (expected punishments) for various criminal acts. People commit crimes so long as they are willing to pay the price society charges, just as many of us might risk a parking or speeding ticket by disobeying traffic laws.

Because criminals and potential criminals rarely have accurate information about the probabilities of arrest, conviction and imprisonment, their personal assessments of the expected punishments vary widely. Some overestimate their probability of success, while others underestimate it. More skillful and intelligent criminals face better odds of getting away with their crimes. Despite the element of subjectivity, if the (objectively measured) expected cost of crime to criminals declines, crime increases and vice versa.22 This theory is consistent with public opinion23 and with the perceptions of potential criminals.24 And it is supported by considerable statistical evidence.25

How Expected Punishment Is Calculated. Four adverse events must occur before a criminal ends up in prison. The criminal must be arrested, prosecuted, convicted and sentenced to prison. As a result, the expected punishment for crime depends on a number of conditional probabilities: the probability of being arrested for a crime after it is committed; the probability of being prosecuted after an arrest; the probability of being convicted if prosecuted; and the probability of going to prison if convicted.

As Table I shows, the expected punishment is the result of multiplying all four of these probabilities and then multiplying that result by the average or median time served. Even if each of the separate probabilities is reasonably high, their product can be quite low. Suppose, for example, that each was one-half.26 The overall probability that a criminal would spend time in prison would be only 6.25 percent.

Expected punishment is not the length of time criminals actually remain in prison; those released in 1994 served an average of three years.27 To reiterate, expected punishment has to do with probabilities and takes into account that 98 percent of all crimes in Texas do not result in any prison time.

The Probability of Arrest.28 Table II shows the percentage of crimes “cleared by arrest” in mid-1995 in Texas. Note the dramatic decline in arrest rates over the past 34 years, even for the most serious crimes.29

• Since 1960, the probability of being arrested for committing a murder has fallen by 21 percent.

• The probability of arrest for rape has dropped 22 percent, for robbery 23 percent and for burglary 51 percent.

Overall, during the 1980s, only one in five reported serious crimes in Texas was cleared by arrest.30 In the first half of 1995, the statewide clearance rate rose to 24 percent. In Japan, by contrast, 50 percent of serious crimes are cleared by arrest. And Japan, with a population of 122 million, has fewer murders each year than Texas, with a population of only 18.3 million.31

"Four adverse events have to occur before a criminal actually winds up in prison."

The Probability of Going to Prison. In contrast to the probability of arrest, the probability of imprisonment if one is arrested has increased substantially for most crimes. [See Table III.] Still, police in Texas arrested nearly 215,000 people for violent and property crimes in 1994, but only 27,000 — or 13 percent of those arrested — went to prison. That means that 87 out of every 100 people arrested for crimes of violence or against property in Texas served no time in state prison.32 Despite that fact, more people who are arrested are now going to prison and staying there longer.

"The arrest rates have declined for the most serious crimes."

Expected Punishment in Texas. A comparison of Figures II and IV shows the difference between the average time spent in prison by people who are imprisoned and the expected punishment at the time a crime is committed:33

• Murderers in prison will average spending 12.8 years there, but the expected punishment for someone who commits a murder is 9.2 years.

• Although the actual time served in prison by rapists averages 11.8 years, the expected punishment for committing rape is only 19.4 months.

• The actual time served in prison for robbery averages 7.5 years, vs. expected punishment of only 6.4 months.

For other crimes, Figure IV shows these results:

• Expected punishment is 37.7 days for aggravated assault, 26.7 days for burglary, 8.7 days for motor vehicle theft and 2.4 days for larceny.

• Expected punishment for all crimes of violence is 168 days and for property crimes 8.7 days.

• Overall, the average expected punishment for all serious crimes is 33.2 days.

If many of these numbers seem low, they are. For this reason, crime still pays for many criminals. Nonetheless, the expected cost of crime to criminals is much higher than it used to be.

The Change in Expected Punishment Over Time. Increasing the prison time served severalfold has had a dramatic effect on expected punishment for every type of crime in Texas.

• During the six-year period 1988 to 1994, expected punishment rose 360 percent for murder and 266 percent for rape.

• It rose 167 percent for larceny, 360 percent for aggravated assault and 299 percent for burglary.

• It rose 220 percent for robbery and 222 percent for motor vehicle theft.

On the average, the crimes with the longest expected prison terms (murder, rape, robbery and assault) are the crimes least frequently committed, comprising only about 12 percent of all serious crimes in Texas. The remaining 88 percent of serious crimes carry an expected prison term of only a few days.34

"The probability of going to prison has increased for most crimes, but 87 of every 100 people arrested for crimes of violence or crimes against property serve no time."

Expected Punishment and the Crime Rate. Figure V shows the relationship between the overall expectation of punishment and the crime rate over the past 34 years. As the figure indicates:35

• Expected punishment fell sharply from 1965 to 1975, coinciding with a steep rise in the crime rate.

• Although the crime rate continued to climb, the rate of increase moderated from 1975 to 1980 — a period when expected punishment rose.

"Since 1991 a drastic increase in expected punishment has coincided with a major decline in crime."

• Expected punishment began falling again in the early 1980s, and by 1985 the crime rate had resumed a steep rise.

• Expected punishment began rising again in 1988, and this time the crime rate fell moderately.

• Since 1991 a drastic increase in expected punishment has coincided with a major decline in crime.

Table IV, comparing 1991 and 1994, shows that this relationship also holds across the range of specific types of crime except for aggravated assault, which rose 1 percent during the period. The reason for the one exception is not clear, although it could be related in part to an increase in violent crime by juveniles.