Advocates of corporal punishment argue that it is more likely than any alternative to prevent offenders from committing further criminal acts, and that it is also an exceptionally strong deterrent to potential offenders. These claims have been subjected to some empirical investigation, especially by the Cadogan Committee, whose research was continued in 1960 by the Home Office Research Unit for ACTO.
Individual deterrence. Part of the research carried out by the Cadogan Committee and ACTO covered 3,023 cases of robbery with violence (virtually the only offense for which corporal punishment was imposed) between 1921 and 1947. Offenders were divided into two groups: those previously convicted of serious crimes and those not previously convicted. In both categories, offenders who were not flogged showed slightly better subsequent records. Those who were flogged seemed slightly more likely to be convicted again of robbery with violence, although the numbers were small and the differences not statistically significant (Cadogan Committee; Advisory Council on the Treatment of Offenders). These findings suggested that flogging was not especially effective as an individual deterrent, but they were not conclusive: the groups of those flogged and not flogged were not properly matched, nor were the sentences randomly assigned, for some judges habitually made more use of the penalty than others.
General deterrence. The Cadogan Committee devoted special attention to five cases of corporal punishment used as an exemplary sentence in response to major outbreaks of crimes for which, according to public opinion, the penalty was particularly suitable. The committee found that in some cases the facts plainly contradicted such beliefs and that reductions in crime could just as plausibly be attributed to causes other than the penalties imposed on offenders. It also noted that the incidence of robbery with violence in England and Wales had declined steadily in the years before World War I notwithstanding infrequent and decreasing use of corporal punishment, whereas in the postwar years it had tended to increase despite a much greater and increasing resort to floggings. It was also shown that between 1890 and 1934 the incidence of robbery in England and Wales (where corporal punishment might have served as a deterrent) declined more slowly than in Scotland, where corporal punishment was not inflicted for those offenses (Cadogan Committee).
ACTO also compared the incidence of robbery with violence in England and Wales before and after corporal punishment was abolished as a judicial penalty in 1948. The number of robberies reported to the police increased steadily during and after World War II, although corporal punishment was employed more frequently than before the war. After 1948, however, there was a marked downward trend, and until 1957 instances of robbery remained well below the 1948 level. The causes of this reduction were unknown, but ACTO inferred that corporal punishment had not been a strong deterrent immediately before its abolition and noted that abolition was not followed by an increase in the offenses for which it had previously been imposed (Advisory Council on the Treatment of Offenders). In short, no evidence proved that corporal punishment provided more deterrence than imprisonment, to which it commonly served as an alternative penalty before abolition. Canadian and New Zealand studies confirmed these findings (Canada, Parliament; New Zealand Department of Justice).