Lincolnshire Police force is to be investigated over the collapse of a major drugs trial. The investigation centres on allegations that officers recorded a defendant's conversation with his solicitor.
It resulted in the case against 11 people accused of supplying heroin being stopped earlier this month.
Judge Michael Heath described the bugging as outrageous and a breach of a fundamental right.
Lincolnshire Police have voluntarily referred the matter to the new Independent Police Complaints Commission (IPCC).
The investigation will be carried out by West Yorkshire Police, under the IPCC's Commissioner for Lincolnshire, Len Jackson.
It is expected to take several months.