A barrister and part-time judge accused of lying to police investigating the Chris Huhne speeding points saga got herself into ''the most frightful mess'', her barrister has told jurors.

But trying to pervert the course of justice would have been a ''reverse of nature'' for a lawyer like Constance Briscoe, Patrick Gibbs QC told Southwark Crown Court.

Briscoe, 56, is on trial accused of trying to pervert the course of justice in connection with the investigation into how disgraced Cabinet minister Huhne passed speeding points to his then-wife Vicky Pryce a decade ago.

Both Huhne and Pryce were jailed last year after he pleaded guilty and she was convicted by a jury. They have since been released.

Briscoe, who has been suspended since her arrest in October 2012, denies three counts of intending to pervert the course of public justice.

She is alleged to have provided police with two inaccurate statements about her role as an intermediary between Pryce and reporters; producing an altered copy of a statement and then getting a document expert to view the wrong version of that statement in a bid to mislead the court.

Closing the defence case, Mr Gibbs told the jury of seven women and five men that trying to pervert the course of justice would be a ''reverse of nature'' for a barrister like Briscoe.

He said: ''It's like a doctor trying to poison someone. It's like you as a parent encouraging your child to run across a busy road.

''It's contrary to everything that is supposed to be natural,'' he said, adding: ''Everything you are trained to do.''

Earlier he told jurors the 56-year-old had found herself with a conflict of loyalties between Vicky Pryce and the police.

He said: ''My central suggestion to you... is what we may have here is a lawyer above all else, who never asked to get involved in all of this but who found herself in a position where she felt obliged to speak to the police but was reluctant to make a statement because of a conflict of loyalties, both of which loyalties - to the police and Vicky Pryce - were both decent loyalties, heartfelt loyalties.

''And that she tried to satisfy both loyalties by leaving some things out of her statements, but not telling any lies.''

He added: ''What has happened here is that she has got herself into the most frightful mess.

''It's not all her fault but some is, you may even say most is, and she is not very good at facing up to that, either before court or in court, because her pride gets in the way.''

Mr Gibb urged jurors to see the difference between someone who could be seen as ''too clever by half'' or someone who had deliberately broken the law.

''It (being too clever by half) can make you a bit of a nightmare as a person, it can get you actually into a terrible mess,'' he told the court.

The barrister went on: ''I am going to suggest that one of your jobs may be to distinguish or try to distinguish between trying to be too clever and being too clever by half on the one hand, and trying to pervert the course of justice on the other, because it's the second of those things that Ms Briscoe is accused of.

''They are clearly different things, in fact there is all the difference in the world between them.''