LeAnn Rimes medical history could disprove her lawsuit against schoolteacher Kimberly Smiley.

The singer brought an invasion of privacy case last week against high school teacher and mother-of-four Kimberly Smiley claiming she was victimised on Twitter.

LeAnn says that Kimberly recorded a phone call in which the star was extremely profane, calling the woman a "b***h".

A prominent defence attorney believes that LeAnn really has no case.

"If this goes to court, everything is fair game in either to prove your case or defend against allegations," Los Angeles Criminal Defence Attorney Dana Cole told Radar Online.

"If LeAnn is suing Kimberly then she becomes an open book and her medical history can be relevant and admissible in court. So if she claims that Kimberly is causing her emotional distress, her lawyers can say, 'No, we want to look at your medical records because you could have been suffering anxiety for a lot of things before, which caused you to enter a rehab or a mental health institution.' Your entire medical file becomes an open book when you choose to sue.

"Public figures don't really have much of a claim to invasion of privacy."