Wesley Ballantine should have never died. The 17-year-old was bright, vibrant, and hungry for life, a true "lion among humans".

When he wasn't studying a broking course or working as a trades assistant, he would get lost in his music, playing blues, flamenco and jazz on his guitar for hours on end. A talented performer with an eclectic taste, he wanted to learn to play the trumpet next and become a businessman.

"His friends described him as the biggest man at the table," his mother Regan Ballantine said. "I don't know how to describe him, he was larger than life."

But in the early hours of January 5, 2017, his life was brutally cut short after he plummeted 12 metres to his death while installing a glass ceiling during the refurbishment of the Old Post Office building in the Perth CBD.

He was rushed to Royal Perth Hospital but could not be saved.

Jarring images of the construction site obtained by WAtoday show Wesley had been walking on steel beams and wooden planks around open voids prior to his death. The floor was covered in extension cords and other construction materials, making the work more perilous.

Wesley wasn't wearing a safety harness because there was nowhere to hook it.

Ms Ballantine remembers the shock of the call from the police and the earth suddenly slipping out from underneath her. "Wesley has fallen passed away," she remembers the officer at the other end of the line saying.

"You just don't believe it," she said. "It was like I was watching a movie of myself like it wasn't real what they were telling me."

For months, Ms Ballantine lived in a state of shock so deep she couldn't even shed tears at her son's funeral. She lived in the hope the system would right the wrongs and serve justice for Wesley. It was designed to protect workers.

But nearly a year and a half after Wesley fell to his death, during a meeting with WorkSafe, reality came crashing down like a pile of bricks.

Valmont, the contractor hired to carry out the refurbishments, would face a maximum fine of $200,000 for Wesley's death. That was if it was slapped with the harshest penalty.

That was about $160,000 below the maximum penalty, and less than a year's salary on minimum wage.

"The system cheated Wes, the system devalued his life, the system protected the businesses, the system favoured the businesses," Ms Ballantine said.

"As a mother and a parent you raise your kids to bring them to the very stage Wesley was at, which was the door to his future, a world of endless possibilities. He just didn't make it through that door.

"I feel so cheated, I feel cheated for Wes and I feel cheated for the efforts and sacrifices and struggles that I made as a mother to get him to that point."

At that moment, it dawned on Ms Ballantine that the system was broken and it needed to be fixed, even if it was too late for Wesley.

It sent her on a quest to campaign for manslaughter laws to be introduced in Western Australia as part of an overhaul of work safety laws.

Now, 3½ years after Wesley's tragic death, the upper house is due to debate the Work Health and Safety Bill 2019, which if passed could see Ms Ballantine's hopes for greater accountability for operators become reality.

Tougher penalties for companies have also been rolled out under a modernised Work Health Safety Act, with level four offences, which include fatalities, now attracting a maximum $2.7 million penalty for first-time offenders and $3.5 million for repeat offenders – up from $500,000 and $625,000, respectively.

First-time offence fines have also jumped from $50,000 to $450,000 while repeat offenders face $570,000 fines, up from $62,500.

Under these new penalties, two companies are facing a combined $4.7 million in fines over the death of young plumber Ryan Duffus in Mosman Park in a landmark case for workplace safety.

If Valmont had been fined under current penalties, its fine would have likely been 7½ times higher.

The penalties are a small victory for fierce advocates like Ms Ballantine, who said campaigning for industrial manslaughter laws "resuscitated her".

"Wesley's death took so much from me but it gifted me real purpose," she said. "It's a gift to be able to take something so tragic and transform it into something good for others."

Although she was worried about her future without Wesley and missed hearing the sound of his guitar after coming home from a long day, Ms Ballantine said she was determined to live the happy life Wesley didn't get the chance to live.

"Life's asked me to bear the unbearable," she said.

"I've seen my son's body after it's fallen 12 metres onto a concrete floor on my 39th birthday, I've given a eulogy at my own son's funeral. It goes against the laws of nature.

"But I'm determined to live a happy and fulfilling life and I do that not only for myself but for the fact that my son doesn't get to live a life, the least I can do is value mine."