OPPORTUNITIES , PRECIPITATORS AND CRIMINAL DECISIONS : A REPLY TO WORTLEY ' S CRITIQUE OF SITUATIONAL CRIME PREVENTION by Derek B . Cornish

Clarke's classification of situational crime prevention techniques is designed to provide a conceptual analysis of situational strategies, and to offer practical guidance on their use in reducing criminal opportunities. It has developed in parallel with a long program of empirical research, conducted by many researchers, on the situational determinants and the prevention of a wide variety of crimes. For this reason the classification has been subject to constant revision and updating, of which Clarke's (1997) version, which lists 16 such techniques, is the latest. Recently, Wortley (2001) has suggested the need to augment the existing classification, which deals with the analysis of situational opportunities, with a complementary analysis of situational precipitators. These are factors within the crime setting itself that may prompt, provoke, pressure, or permit an individual to offend. The present chapter examines the assumptions underlying the development of situational crime prevention, and offers some views about the theoretical and practical significance of Wortley's suggested additions and revisions. It concludes by proposing a revised classificaCrime Prevention Studies, vol. 16 (2003), pp.41-96. Derek B. Cornish and Ronald V. Clarke tion of 25 techniques to take immediate practical account of some of the concerns raised above. A NEW CRITIQUE OF SITUATIONAL CRIME PREVENTION Until recently, Clarke's (1992, 1997; Clarke and Homel, 1997) classification of situational techniques has been seen as providing a systematic and comprehensive review of methods of environmental crime prevention, and has served to guide practical efforts to reduce offending. Such criticism as has been made of situational techniques has tended to concentrate on their alleged failure to tackle the root causes of crime — that is, to address issues of criminal motivation, and to support programs of social and individual crime prevention — or on the putative threats they pose to civil liberties. These issues have been exhaustively explored elsewhere (von Hirsch et al., 2000) and will not be further examined in this chapter. Recently, however, in a series of carefully argued papers (1996, 1997, 1998, 2001) and in his book, Situational Prison Control (2002), Wortley has offered a challenge from within the field of environmental psychology itself to the theory and practice of situational crime prevention. Wortley s critique centers on what he views as the undue and potentially damaging preoccupation with opportunity variables when discussing offender decision making and situational prevention. He contrasts this with the relative neglect of other situational forces (termed "precipitators") within the crime setting that serve to motivate offenders. He identifies four types of precipitator — prompts; pressures; permissions; and provocations — each of which may provide situationally-generated motivation to the hitherto unmotivated. He goes on to offer a two-stage model of situational crime prevention that views offending as the outcome of two sets of situational forces: precipitating factors and regulating factors. Temporal priority is given to the influence of precipitators in motivating the offender, these being followed by the influence of opportunities in regulating whether or not offending actually occurs. He concludes that controlling precipitators is just as important as regulating opportunities, and provides an additional and complementary set of situational crime prevention techniques to control precipitators, claiming that these supply the missing half of a new and more comprehensive situational approach to crime prevention practice. Lastly, he suggests that the development of such a situational framework might better explain and minimize the iatrogenic effects of situational measures in some circumstances.