It was the first appearance on the criminal charge.
Castle said Newsroom would mount a "strenuous denial" of the charge.
"It is the position of Newsroom that neither did it intend to offend … indeed it did not," he said.
Castle said Newsroom had tried to obtain information about the allegations from police.
They refused, and the charge was laid soon after.
Judge Farish cut Castle off and said it was "not the time" to speak to the allegations, it was a simple first appearance and she expected a plea to be entered.
Castle entered a not guilty plea today.
A case review hearing will be held to go through the facts of the allegations on September 3.
The court was reminded that the family at the centre of the alleged breach could not be identified due to statutory suppression orders.
Outside court Reid spoke to waiting media.
She said the charge was the result of the "heavy hand of Crown Law".
"It seems nothing short of ridiculous that we are now facing criminal charges," she said.
"We are journalists, not criminals - and if this is how Crown Law is going to treat the media who expose bad practice ... we should all be afraid.
"We need a free and independent press because the state needs to be held to account - it always has and it always will and that's why it's said journalism is the cornerstone of democracy."
Newsroom co-founders Tim Murphy and Mark Jennings were not in court for today's hearing.
In a piece published on Newsroom's website in May Murphy confirmed police were investigating the publication over a story it published in late 2020 about a "reverse uplift" of children by Oranga Tamariki staff.
The Solicitor-General urged the High Court to order the removal of the story from the Newsroom website, claiming it contained information that could identify the family involved in the case.
By law, anyone involved in Family Court proceedings cannot be identified by the media.
All child uplifts are done under Family Court orders and fall under that rule.
Newsroom disputed the Solicitor-General's claim but after negotiating with the Crown Law Office, made changes to the video that accompanied the story to alleviate concerns.
Murphy said the CLO then went "without notice" to the High Court and successfully sought an interim injunction order preventing the video from being published further.
Further, he said the CLO "simultaneously referred the video story to the police for investigation under a supposed breach of the Family Court Act over the identification of the children".
After investigating, police charged Newsroom with a breach.
The maximum penalty for such a breach is a maximum of three months imprisonment, or fines of $2000 fine for an individual, or $10,000 for an organisation.
In May Murphy rejected any wrongdoing by Newsroom.
"Newsroom does not accept the video content breached the Family Court Act," he said in a piece published on the outlet's website.
"Newsroom still believes the second video did not identify the children involved, and that it acted responsibly in discussions with Crown Law.
"There was no complaint to Newsroom from the whānau or others involved in the story that the children's identities had been made known."
He maintained the story was a matter of public interest.
"The case highlighted in the video led directly to Children's Minister Kelvin Davis seeking a 'please explain' from the agency and then directing Oranga Tamariki to stop the new policy of 'reverse uplifts' under which Māori children around the country who had been put in permanent care were being summarily removed and taken, in this case, to unknown and distant whānau," he said.
"A Māori advisory panel was appointed from outside the ministry and the chief executive of OT, Grainne Moss, later resigned."
Veteran journalist Melanie Reid, the reporter behind the story, also stood by her work.
"With all due respect, we just can't agree with the claims by Crown Law that this video identified those children," she said.
"It all just feels like a punishment of the media for revealing the state's misuse of power. It is how whānau feel when the state moves against them and their children.
"This video highlighted a policy that was wrong and damaging - which was cancelled by the minister after viewing it - and this is how the system carries on afterwards."
