Bradley, J. (2018). Is stop and search a deterrent? BMJ, K2122.

Full letter: Torjesen says that Scotland was successful in reducing knife
crime by adopting a public health approach and not by an
increase in enforcement activity and resources.
The debate about the effects of stop and search on crime has
been ongoing for many years now. Proponents are often
convinced from personal experiences or beliefs that stop and
search can reduce crime rates, whereas opponents emphasise
the contradictory evidence base and question the effect and
proportion of searches that led to arrests or other criminal
enforcement measures.
A large scale analysis undertaken by the College of Policing in
2017 using Metropolitan Police Service panel data from 2004
to 2014 concluded that higher rates of stop and search were
followed occasionally by very slightly lower crime rates. Most
of the measured associations were, however, weak and
inconsistent and provided limited evidence that stop and search have a deterrent effect on crime.