"It's certainly possible," he said.
"The first thing to note is that it's not unlawful to record a conversation that you're a party to, even if you don't tell the other party you're recording it.
"Private investigators are not allowed to record stuff like that but ordinary citizens are, even if they don't tell the parties they're recording it."
Hannan, an experienced privacy lawyer, said Bridges could apply for an injunction on the basis of breach of confidential information.
"If the information has got the necessary level of confidentiality then you potentially can get an injunction on someone who has come by it from disclosing it.
"I think Simon Bridges would have a pretty reasonable basis that these were intended to be confidential conversations," he said.
Hannan said Ross could argue he was releasing audio recordings on the basis of public interest.
If it's deemed the recordings talk about the administration of Government, Ross could argue the public has a legitimate interest in their discussion.
However, Wellington media lawyer Steven Price told the Herald Bridges could argue against the recordings being released under public interest.
"If the recording has some significance for some sort of electoral offence then I think you've got a pretty easy public interest argument.
"If the recording doesn't, which is what Simon Bridges seems to be saying, then I'm not sure you do have a public interest defence.
"But there may be public interest in the way Bridges is discussing various ethnicities and the way he is describing the competency of some of his employees," Price said.
Hannan said getting an injunction against Ross would be difficult and could be counterproductive as well.
"He would need to have a careful judgment about whether or not overall the downside in terms of people thinking he must have something to hide."
