Countdown star Rachel Riley was wrongly accused of being responsible for death threats sent to a teenager when she tried to expose Labour antisemitism, a court has heard.
Ms Riley was branded a hypocrite and and a bully by journalist Mike Sivier in his Labour-supporting blog post on the Vox Political website.
He said she had "cold shouldered" a vulnerable 16-year-old and described her as "serial abuser Rachel Riley".
It was in response to a Guardian article which reported that the 33-year-old presenter needing extra security when filming.
Ms Riley and Eastenders star Tracy-Ann Oberman who plays Chrissie Watts in the show, have been active campaigners against the antisemitism which has plagued the Labour Party.
William Bennett QC, representing Ms Riley, said at a pre-trial hearing: 'We say our case is even stronger in that those people reading on a smartphone would not follow the hyperlink."
Mr Justice Matthew Nicklin, presiding over the case, interjected that the hyperlinks to the other article were not unlike the sources at the end of a Wikipedia entry.
"Very few people are going to bother following hyperlinks unless they consider them necessary for their understanding of what the main article is," the judge said.
Mr Bennett told the court that Mr Sivier's article was in fact presented as a factual piece rather than opinion.
The article stated Riley had "cold-shouldered" a young girl with anxiety problems, which led to her supporters harassing her and sending death threats.
"It is not an expression of opinion it a factual allegation. It says that Ms Riley's behaviour has caused the appalling behaviour towards this young woman," said Mr Bennett.
"We say that adds to the defamatory sting, because that makes Ms Riley to be an even worse person because of the suffering which was caused to this young woman."
Mr Bennett read a line from the article which contrasted Ms Riley needing extra security while contributing to the death threats against the young girl.
"That is not an expression of opinion. That is an indictment of Ms Riley," he said.
"The defamatory sting is that Ms Riley is a hypocrite because she gets protection from being abused while she has repeatedly abused this young woman."
David Mitchell, representing Mr Sivier, argued that his client's article cannot be read separately from two longer articles it cited.
"He is careful to advise his readers that this is the evidential basis on which he makes his case," said Mr Mitchell.
The linked articles alleged Riley became involved in the "second trench" of the bullying of the teenager, who suffers from anxiety.
"There follows the tweet from the claimant at the bottom of the page where effectively she has drawn issue with the child's father for seeking to speak out and protect his daughter," said Mr Mitchell.
Mr Mitchell said that the fact that the article was within the "live, fast-moving and fiendish" debate on antisemetism marked it as opinion.
"That goes to the essence of what this is about.
"It is an opinion piece on a deeply controversial and fast-moving matter of political current affairs on which Mr Sivier was seeking to provide contribution," said Mr Mitchell.
The site where the article is published, due to a political slant, also marked the article as opinion, said Mr Mitchell.
"This is an interactive format where people are encouraged to leave their own views," he said.
"Mr Sivier is using the words, comment and debate setting out his own background as someone who has been falsely accused of antisemitism by some of the people Ms Riley is allied with."
Mr Mitchell argued that in no point in the article did Mr Sivier say Ms Riley encouraged her fans to harass the teenager.
"These are consequences which he doesn't directly attribute to the claimant but says she has been recklessly irresponsible," he added.
The court heard that as a consequence of the harassment the girl received death threats, her Twitter account was hacked and someone close to her attempted to sell her story to The Sun.
Mr Justice Nicklin said that reading the article gives the impression that Ms Riley's actions led to the harassment of the teenager.
"As a consequence the vulnerable victim has been subject to appalling abuse including death threats. It is the child and not the claimant that is the victim," said Mr Justice Nicklin.
"A publication can of course contain both a defamatory allegation of fact and a defamatory opinion. A defence of opinion can only defend the latter."
An 'ordinary, reasonable reader' would not have needed to click on the linked articles in order to reach their own conclusions, ruled the judge.
"The article was self-contained and it was not necessary to follow the links to understand the points made by the defendant," he said.
The judge ruled that while the part of the article calling Ms Riley a hypocrite is opinion, the claims about the harassment campaign are presented as fact.
Mr Sivier has until the January 29 to present his new defence, ahead of a trial in the new year.