Mrs Blair says she has 'nothing personal' against Gordon Brown
Cherie Blair has insisted she will not resign as a judge after a senior barrister said publishing her memoirs had brought the law into disrepute.
Gerald Butler QC said her actions were "not appropriate" and "she should not continue to sit as a recorder".
But Mrs Blair, wife of former PM Tony Blair, told BBC Radio 4's Woman's Hour she "certainly" would not go, as the law was "really important to my life".
She also faces criticism for writing about the death of Dr David Kelly.
Mrs Blair has reportedly received a £1m advance for the publication of her memoirs, which include details of her family life and opinions of leading political figures.
'A good read'
In them she describes Mr Brown, when chancellor, as "rattling the keys" over her husband in his desperation to take over power.
But Ms Blair told Woman's Hour: "I wanted my book to be a good read. As an advocate we use a good phrase to make a good point and it was a good phrase to make a good point...
"It is no secret that Gordon wanted to succeed Tony and that Tony wanted Gordon to succeed him. It's not an ignoble ambition to want to be prime minister."
She added that her relationship with Mr Brown had not been "as difficult" as some people thought, and that they had not had much time to socialise after Labour took power in 1997.
'Lack of decency'
Mrs Blair said money had not been her main motivation in writing her life story, but the urge to "speak for myself" after years of press reports.
The publication of the memoirs, coming shortly after those of former deputy prime minister John Prescott, has led to claims Mrs Blair is cashing-in and damaging Mr Brown's government at an already difficult time.
Earlier, Mr Butler told the Evening Standard newspaper: "If she wants to tread this path of making outrageous comments it's up to her, but I don't think this is a job for a judge.
"It shows a complete lack of decency."
Mrs Blair said: "I'm sorry that he feels like that."
She added that the comments had been based on press "extracts" rather than reading the whole book.
Mrs Blair said: "The law is very much a really important part of my life. I enjoy the law and I intend to continue to practise."
Speaking later at his monthly media conference in Downing Street, Mr Brown was asked how he felt about Mrs Blair.
He replied: "I have enjoyed working with both Tony Blair and Cherie Blair over the years and I have got nothing but praise for the work they did for our country, and continue to do."
Dr Kelly's brother-in-law, Derek Vawdrey, told the Daily Mail this week Mrs Blair should be "ashamed of herself" for writing about the government scientist's suicide.
In the book, Mrs Blair describes her husband's distraught reaction to the news.
Asked about Mr Vaudrey's comments, she said: "I'm sorry he feels like that but it's very much a part of the story."
You can hear Cherie Blair's interview at the Woman's Hour website.