A Labour candidate is dishonest and not fit to be an MP, a court has been told.
Anna Turley claims the Unite union libelled her in an article on an internet blog relating to an application she made for membership.
Ms Turley who is contesting the seat for Redcar on Teesside, is also suing Stephen Walker, a journalist who writes and publishes the Skwawkbox blog.
Lawyers for the union told the High Court Ms Turley's dishonesty "permeates through every part of the case".
Ms Turley claims the blog article, which contained a press statement from Unite, libelled her and that Unite misused her private information.
Unite and Mr Walker are fighting the case at a High Court trial in London.
Their barrister, Anthony Hudson QC, told Mr Justice Nicklin that Ms Turley was dishonest and "regrettably, not fit to be an MP".
He added that Ms Turley's dishonesty "permeates through every part of the case".
Barrister Kate Wilson, for Ms Turley, said her client was on the "moderate" wing of Labour.
She said Unite under leader Len McCluskey was "the most" or "one of the most" important supporters of Jeremy Corbyn's leadership of Labour.
The Skwawkbox blog was supportive of Unite under Mr McCluskey's leadership, she added.
Ms Wilson said in December 2016, Ms Turley mistakenly applied to be a Unite member under a "Community" membership category, which was aimed at people not in paid employment.
She said when Ms Turley discovered the error in March 2017 she sought to transfer to the "appropriate membership".
But the Skwawkbox article, which appeared the following month, implied Ms Turley had "acted dishonestly", Ms Wilson said.
Ms Turley is seeking damages for an as-yet undisclosed figure.
The trial continues.