Coop the black labrador rushes through the open sliding door of her home, a tornado of wagging tail and licking tongue.

But as soon as her owner Tessa Stow clips on Coop's work coat, she transforms.

"She's a pretty excited dog without her uniform on. She's very naughty," Ms Stow told 7.30.

"But once she has her coat and lead on, she becomes a working dog."

Coop is about to make the three hour commute from her home in country Victoria to her job in Melbourne.

Coop is not allowed to be seen by jurors when in the witness box. ( ABC News: Lauren Day )

She is the first dog in Australia to be allowed in a courtroom and Ms Stow said she is highly trained to be almost emotionally "bulletproof".

"I train along the lines of a service dog, so [it takes] up to two years, train them to pass the public access test and then I train specific tasks," Ms Stow said.

"Someone who's scratching, someone who starts to rock, someone who cries, someone who puts their head in their hands, the dog will pick up really strong emotion from people."

"Half of it's taught and half of it's intuitive, so this is where you have to have the right dog, and not all dogs are suitable."

How Coop came to be in the witness box

Tessa Stow has trained Coop to be emotionally 'bulletproof' ( ABC News: Lauren Day )

Ms Stow first had the idea of using dogs in Victoria's court system after her own painful experience of it.

"In 1988 I was involved in giving evidence in a traumatic case and I found it really really hard to do," she said.

"Not long after that, I became a vet nurse and really saw the impact and power that animals had on their owners.

"So I put the two together, and thought it would be absolutely fantastic to be able to train a dog to help in a court process.

"And that's when I bought Coop at eight weeks of age."

Meanwhile, at the Office of Public Prosecutions, Julie Morrison had the same idea.

"After I started with the OPP I began to think, I wonder if there's a space for dogs in the legal setting working with victims and witnesses," she told 7.30.

"I started doing some research and saw that there was nothing happening in Australia, but yet in America and Canada programs have been running since 2003 where dogs support people in court.

"I began to think, well, could we do something here?"

Ms Morrison got in touch with Ms Stow and in September 2017, Coop landed a job at the Office of Public Prosecutions.

'The feelings she gave me were just overwhelming'

Leah Stephens said Coop helped her talk about the worst experience of her life. ( ABC News: Lauren Day )

Coop has already helped around 140 victims and witnesses of crime in over 100 cases, the vast majority involving sexual assault.

One of the people she helped give evidence was Leah Stephens.

"She was offered to me the day before to come into my video box at the hardest time of my life," she told 7.30.

"And as soon as we laid eyes upon each other, I forgot where I was."

Ms Stephens does not want to discuss the details of her case publicly, but said Coop's presence in the remote witness room helped her talk about the worst experience of her life.

"She was like my mother and my grandmother put together, and the feelings that she gave me were just overwhelming," Ms Stephens said.

"She's really, really important to people in the world who have no-one and nothing at a time when they're so desperate to grab onto anything that's real — and Coop is so real."

Ms Stow said Coop had also helped child victims in counselling.

"Counsellors had a child come in for six weeks, and the child's just been non-verbal. And then on the first day of meeting Coop, they walk in, lie down, lay on her and just lift her ear and tell their story," Ms Stow said.

"The counsellor's still in the room, they get to hear, but the child hasn't been able to tell another human because they don't trust humans any more.

"But they trust the dog."

Lessons to be learned from US court dog programs

Tessa Stow is training the next generation of court support dogs. ( ABC News: Lauren Day )

With Coop's services in high demand, Ms Stow is busy training the next generation of court dogs.

She estimates only two of her six pups in training will be suitable.

"It is a lot of work and anyone who trains service dogs will understand that," she said.

"Not all of the in-training court dogs that I'm training will make it, but they will go to other work.

"They might go to a veteran as a service dog, or they'll go as a therapy dog to a school, so they still have other places of work to go to."

As well as more dogs, Ms Morrison said more research was needed.

Julie Morrison helped instigate the court dog program at the OPP. ( ABC News: Lauren Day )

"In America, dogs are allowed in courtrooms in 37 states, so they're way ahead of us in what they've been doing and they've been doing," she said.

"Not only have they done studies about how dogs can reduce stress levels, they've done studies about dogs in court programs, where they've shown the reduced stress levels basically lead to better evidence which benefits the whole system."

She is about to head to the US to study the use of dogs in the American justice system and how it could be applied in Australia.

"Whenever we want to use Coop we need to ask permission from the courts, which is fair enough, but that means of course that sometimes the courts can say no, and we have had that happen to us on two occasions."

"In America, in six states, they've actually made legislative change giving people the right to have a dog with them as they give their evidence and I'm really keen to see how they manage to do that."

She hopes one day, every witness in every court in Australia will have access to a support dog.

Watch this story tonight on 7.30.