Prison rights: mandatory drugs tests and performance indicators for prisons.

Mandatory drugs testing of prisoners applies throughout England and Wales. Data from the 1995 pilot study in eight prisons show that the proportion testing positive for opiates or benzodiazepines rose from 4.1% to 7.4% between the first and second phase of random testing and that there was a 20% increase over 1993-4 in the provisional total of assaults for 1995. Interpretation of these data is difficult, but this is no excuse for prevarication over the danger that this policy may induce inmates to switch from cannabis (which has a negligible public health risk) to injectable class A drugs (a serious public health risk) in prison. The performance indicators for misuse of drugs that are based on the random mandatory drugs testing programme lack relevant covariate information about the individuals tested and are not reliable or timely for individual prisons.