[2] Campbell was the watershed moment where the tort of "misuse of private information" became distinguished in scope from that relating to breach of confidence, as the former does not require "an initial confidential relationship.
[4] While it will be obvious what may constitute public (as opposed to private) information in most cases, there will be times where it will need to be assessed as to whether disclosure of information would give substantial offence to an ordinary individual, as noted in Australia by Gleeson CJ in 2001: An activity is not private simply because it is not done in public.
The requirement that disclosure or observation of information or conduct would be highly offensive to a reasonable person of ordinary sensibilities is in many circumstances a useful practical test of what is private.
[5]As originally recognized in Campbell, a cause of action was restricted to disclosures of information or activities in which the plaintiff had a reasonable expectation of privacy.
[11] While the House of Lords followed the model previously adopted by the High Court of Australia, the other two jurisdictions based their approach on the US Restatement of Torts (Second).