When an objection was raised against disclosure of a particular document that it belongs to a class which in the public interest ought not to be disclosed, whether or not it would be harmful to disclose that class document or the contents of that particular document forming part of the class would be injurious to the interest of the state or the public service, it would be difficult to decide in vacuum the claim because it would almost invariably be supported by an affidavit made either by the Minister or head of the department and if he asserts that to disclose the contents of the document would or might do to the nation or the public service a grave injury, the court out of deference will be slow to question his opinion or to allow any interest, even that of justice, to prevail over it unless there can be shown to exist some factors suggesting either lack of good faith or an error of judgment on the part of the minister or the head of the department or the claim was made in administrative routine without due consideration or to avoid inconvenience or injury to their defence.