Martin Innes, Professor of Police Science at Cardiff University, told ITV News that a single major public inquiry is needed, due to to a number of continuing investigations into policing.
He was speaking after the Home Secretary Theresa May revealed possible links between an allegedly corrupt police officer involved in the investigation into the murder of teenager Stephen Lawrence, and the investigation into the murder of a Welsh private investigator.
Daniel Morgan was found dead in the car park of a London pub in 1987.
Prof Innes told our Correspondent Rob Osborne: "There must be a tipping point where you decide that we can't sustain this drip-drip-drip of corrosive allegations of misconduct."
"If these allegations do start to stack up, you will need a Royal Commission on the police, to address these issues, diagnose what the causes are, and put in place some sort of remedies to stop the problem happening again."