MARY LOU MCDONALD has said every citizen has a right to defend and vindicate their good name, as it emerged her husband has threatened to sue the author of a biography on the Sinn Féin leader.

It has been reported that solicitors acting on behalf of Martin Lanigan issued a letter to Shane Ross in relation to his recently published book.

It is understood the legal action is related to a chapter in the book, entitled Mary Lou McDonald: A Republican Riddle, about the purchase and renovation of their family home in Cabra, Dublin.

Asked about the legal letter today, McDonald said: “Obviously, our system relies on two things – freedom of expression, freedom of the press and also the right of every citizen to defend and vindicate their good name.

“And my husband is a private citizen and I think those rights for private citizens are especially important.”

Ross told the Sunday Independent at the weekend that he was “surprised” to receive the letter.

He said that there was “no allegation in the book of impropriety”, but that the book asked “reasonable questions, which should be answered”.

He said he intended to fully defend any proceedings.

In a statement to the Sunday newspaper, Ross said: “I was surprised to receive the letter from the solicitor for Mary Lou’s husband last week. I had corresponded with Martin when writing the biography, asking to interview him for the book.

“I also contacted Mary Lou’s office seeking to put questions to her. Unfortunately, I received no response in either case.

“I believe it is perfectly appropriate that the ownership of all politician’s properties held jointly with their partners should be transparent and do not in any way accept that the subject is a breach of privacy.

“There is no allegation in the book of impropriety over the refurbishment of their house be either Martin Lanigan or Mary Lou.

“Indeed, it is explicitly stated on page 184: ‘There is nothing to suggest that Mary Lou has ever been involved in anything untoward or has been other than a person of impeccable financial integrity, but she ruthlessly demands transparency of others’.

“The book seeks similar transparency, asking reasonable questions which should be answered. They have been asked before and have never been addressed.”

He added: “It is essential that freedom of speech is not curtailed in the political arena by means of threats of legal action or by misguided claims that privacy has been breached.”

It comes as some senior ministers accused Sinn Féin of using legal threats as a strategy to “stifle debate”.

Both Taoiseach Micheal Martin and Tanaiste Leo Varadkar questioned the party’s use of legal letters.

Last week, Varadkar said that three elected Fine Gael members have received legal letters from Sinn Féin figures.

He questioned whether the legal action was “something more strategic”.

Sinn Féin has previously said that the party does not fund any cases taken by its elected representatives.

“Legal actions are funded by those who have no option but to vindicate their good names in the face of false accusations made by others,” a party spokesman said.