Bureaucrats would have their ability to offer frank and fearless advice curtailed if police documents relating to the reclassification of the Adler A-110 shotgun were released to the public, a tribunal has heard.

More than a year after Adler’s classification was updated by the Council of Australian Governments, NSW police are fighting to prevent the release of the documents which could embarrass state minister Troy Grant if they reveal that his advocacy for a less restrictive classification was at odds with his department’s advice.