Former Independent Insurance chief executive Michael Bright duped his wife Katie into signing Natwest loan documents, she has claimed.
Natwest is attempting to recover £290,000 from Mrs Bright, after she signed a joint loan with Bright.
Bright has since been declared bankrupt.
Natwest's lawyer Reid Minty partner Stephen Moss said the case was in the pleadings stage at the High Court.
He said Katie Bright's lawyers Child & Child had submitted the defence that "she knew nothing and was entirely under the influence of her husband".
"She's claiming he misrepresented to her what she was signing," Moss said.
In response, Moss has submitted requests for further information from Child & Child, to which the legal firm must reply by 18 January.
"There are other documents that she signed with the bank that indicate that was not the case," he said.
Moss said the defence was commonly used by wives in such situations, most notably in the Royal Bank of Scotland v Etridge case .
"The House of Lords says when this defence is raised, the case must go to trial for cross examination," he said.
The onus is on the wife to prove she was coerced.
Child & Child did not return Insurance Times' calls.