The Crown Prosecution Service (CPS) maintains a central record of the number of suspects referred to prosecutors for a pre-charge decision and the number of decisions not to prosecute suspects following the charging decision.
When prosecutors make decisions on cases, they refer to The Code for Crown Prosecutors. The Code contains a two stage test which has to be met before a suspect can be charged; the evidential stage followed by the public interest stage. When deciding whether there is enough evidence to charge, prosecutors must consider whether evidence can be used in court and is reliable and credible, and there is no other material that might affect the sufficiency of evidence. Prosecutors must be satisfied there is enough evidence to provide a "realistic prospect of conviction" against each defendant. At the public interest stage the prosecutor must consider whether a prosecution is required in the public interest. A prosecution will usually take place unless the prosecutor is sure that the public interest factors tending against prosecution outweigh those tending in favour.
The table below shows the volume and percentage of decisions not to prosecute for evidential and public interest reasons for the West Midlands Area in each year from 2013/14 to 2017/18.
No Prosecution - Evidential
No Prosecution - Public Interest
Total of Evidential & Public Interest
Total Decisions Made
Data Source: CPS Management Information System