A former firearms officer has claimed the police complaints watchdog "seems to be treating officers as criminals".
Tony Long was cleared of murder last year, a decade after he shot suspected armed robber Azelle Rodney.
Mr Long, an ex-Metropolitan Police marksman, told Radio Times scrutiny was expected - but he argued "the problem is the interpretation of the rules and the way in which officers are treated".
He said: "Today, the Independent Police Complaints Commission seems to be treating police officers as criminals.
"My former colleagues are saying: 'We will stand by for a Paris-type attack, but when you want us to go out and do an intelligence-led operation against criminals you might need to satisfy us that the intelligence is perfect, or we're not going out'. I think we're quite close to that situation."
Mr Long, who will be featured on Secrets of a Police Marksman on Channel 4 on August 18, added that he was "absolutely confident" his actions in shooting Mr Rodney were correct. He was found not guilty at the Old Bailey in July last year.
Last month official figures revealed that the number of authorised police firearms officers (AFOs) fell for the fourth year in a row.
As of the end of March there were 5,639 AFOs in forces across England and Wales as of March 31 - down by eight compared with the previous year when there were 5,647.
It means the number has dwindled by more than 1,000 in the last five years.
At the time they were published, the Government said the figures did not include an "uplift" in armed policing capability to be delivered over the next two years.
A drive to boost the police service's firearms capacity was launched in the wake of the Paris attacks. However, rank-and-file leaders have repeatedly questioned where the additional personnel will be drawn from.
An IPCC spokesman said: "We recognise the challenging and dangerous circumstances in which firearms officers operate but it is right that when there is a fatality there is an independent investigation.
"Our independent scrutiny should not cause any officer to be concerned about taking on a firearms role."