Barrister Constance Briscoe has been jailed for 16 months for lying to police in ex-cabinet minister Chris Huhne's speeding points case.
Sentencing at the Old Bailey, the judge said Briscoe had "considered respect for the law was for others".
He described the convictions as a "personal tragedy" for the 56-year-old
Briscoe, a part-time judge, was convicted of three counts of intending to pervert the course of justice related to the probe into Huhne.
The jail term is double the eight months that Huhne and his ex-wife Vicky Pryce each received for the original offence in which his speeding points were taken by her.
The BBC's legal correspondent Clive Coleman said it was thought to be the first time anyone who had served as a judge was convicted of perverting the course of justice.
The punishment sent out the message that "nobody is above the law", he added.
Mother-of-two Briscoe, of Clapham, south London, had denied the charges against her.
Jailing her, judge Mr Justice Baker said the conviction would have a "devastating effect" on Briscoe's career, adding that she had been "something of a role model to others".
Jurors had been told that Briscoe helped Pryce, who was a friend and also her neighbour, to reveal information about Huhne's points-swapping to newspapers after the couple split in 2010.
The scandal led to Huhne's resignation and subsequent prosecution.
Mr Justice Baker said Briscoe had tried to hide her role in exposing the story, adding that both she and Pryce had been motivated by "a joint desire to ensure the downfall of Chris Huhne".
Briscoe's position had been compounded by her "deliberately fabricating evidence" when she had feared she would be found out, the judge added.
He said she had been "intimately involved" in negotiations between Pryce and the press, having "courted a significant degree of self-publicity" and become familiar with how the media worked.
The judge said if Briscoe, Huhne and Pryce shared anything in common it was "arrogance by educated individuals who considered respect for the law was for others".
He told her: "I am sure that you realise only too well that such conduct strikes at the heart of our much-cherished system of criminal justice, which is integral and invaluable to the good order of society."
Speaking after the sentencing, senior investigating officer Det Ch Insp John McDermott of Kent Police said: "Constance Briscoe was the architect of her own downfall.
"She has today lost much more than her liberty."
Speaking outside court, Briscoe's mother Carmen Briscoe-Mitchell said of the sentence: "Even one day is justice. If you've done wrong, you've got to pay for it."
Asked what it was like to see her daughter jailed, she added: "What could I do? You should never break the rules. You should always stick to the rules."
Huhne pleaded guilty in February last year to perverting the course of justice. Pryce was convicted after a trial in which she had denied the same offence.
The pair, now divorced, have both completed prison sentences.
When the allegations about Huhne and Pryce emerged in 2011, Briscoe made a witness statement to police on 31 May of that year.
She portrayed herself as an "independent and objective" witness as she claimed Pryce had confided in her in 2003 about Huhne having asked her to take his speeding points.
In a second statement on 16 August 2012 she denied having any contact with journalists or newspapers about the story, but emails obtained by court order ahead of the Huhne-Pryce trial showed that she had spoken to journalists.
Once her involvement was revealed, Briscoe was dropped as a witness in Huhne and Pryce's trial and she was arrested in October 2012.
Meanwhile, a BBC investigation has learned Briscoe is facing a further criminal inquiry about her actions during an unsuccessful libel action brought against her by her mother over Briscoe's childhood memoir, Ugly.
A Scotland Yard spokeswoman said: "We were contacted in September last year regarding an allegation of fraud, which relates to documents that were allegedly fraudulently obtained from Southwark Council. The matter is being investigated by Lewisham CID.
"In April this year, we received information from the BBC in relation to that investigation and that's being reviewed."
The Judicial Conduct Investigations Office said after her conviction on Thursday that Briscoe remained suspended from the judiciary while they carried out an inquiry.