The commission of a crime is a voluntary act which requires not only the presence of a motivated offender, but also the existence of the opportunity for crime. A potential criminal would consider both availability of a prospective target and the absence of an able defense. Such actions have relations to the behaviour of any individual as a rational actor. Any potential criminal would consider rational calculations to ensure the success of his acts.
In these instances deterrent approaches such as environment manipulations, behavioural interventions and criminal prevention policies would eradicate if not limit the number of crimes. Deterrent approaches may also be well-applied to criminal groups since the apprehension of one gang member could lead to the apprehension of the other members, thus, meticulous planning and calculation is necessary in crimes done by groups or by gangs. Group crimes are, more often than not, rational.
However, in most instances, potential criminals are those who are desperate and distracted individuals who suffer psychological disorders or mental defects. Such individuals cannot make rational decisions and are considered impulsive rather than calculative. Such impairment renders these individual incapable of fearing apprehension and punishment and perceiving the severity of the consequences of the crime. Although free from any psychological or mental disorders, in most instances the behaviours of street criminals cannot be reached by formal sanctions because they are usually impulsive, uneducated, and underclass.
Many offenders belong to the lower class of society who is uneducated and wanting of the skills necessary to demand the effects of the modern economy. Such individuals can be hardly deterred from committing crimes by threat of formal sanctions or punishment or by situational crime prevention interventions because they are desperate individuals who have less to lose and with little or without attachment to significant institutions such as family, schools or church.
Also, the effects of deterrent approaches will have little effect to broader classes of crimes such as sex offenses and violent crimes. Nevertheless deterrent approaches may still be effective by formulating intervention policies devised not to manipulate the assessment of a potential criminal but to prevent the act of crime itself.