The NSW Police Association has welcomed a court ruling that allowed a policeman to avoid answering questions about the shooting of a woman on the state's mid-north coast.

In May 2011, Constable Errol Baff fired his gun and injured a woman at Coffs Harbour on the New South Wales mid-north coast.

An investigation was launched, but Constable Baff refused to answer questions citing the common law privilege against self-incrimination.

This week the NSW Supreme Court upheld that privilege, ruling against the Commissioner of Police.

The association's president, Scott Webber, says it was a test case and a win for all police officers.

"What this means is that police officers have the same protections as everyone else," he said.

"The decision could also have implications for critical incident investigations in the future.

"That is, they cannot be forced to answer questions when they have allegedly committed a criminal offence."