A site supervisor failed to prevent the "extraordinarily foolhardy" decision to tie two ladders together, resulting in an untrained worker falling and becoming paraplegic.
Karl Allred, 64, faced the ACT Magistrates Court for the start of sentencing proceedings on Tuesday.
Allred had pleaded guilty to failing to comply with a health and safety duty exposing a person to risk of death or serious injury.
The workplace injury occurred almost three years before Allred's daughter, Ashleigh, was the victim of a horrific highway crash that left her paralysed.
Agreed facts state in 2020 Allred's business, First Class Painting, was subcontracted to undertake a full external repaint of a two-storey townhouse complex in Kingston.
The main contractor, Higgins Coatings, intended for the painters to use fall prevention devices, including a scissor lift and a knuckle boom which required workers to be licenced.
The victim, from Brazil, was not qualified or licenced other than with a general instruction induction card.
The painting team was comprised of the victim, several of his family members and a friend.
None of the workers except for the victim could speak English and the group needed him to translate Allred's instructions into Portuguese.
Allred would usually attend the site in the morning, then leave the victim in charge, before returning that afternoon or the next day.
About 7.15am on June 9, 2020, Allred visited the site and demonstrated how to use a safety harness kit.
In an interview with WorkSafe, Allred stated "we were only just having a bit of a play with the roof kit to see how it all worked and how it would lock in".
Allred then left the site.
During this time the victim set up the roof kit and tied two ladders together with orange strapping, measuring almost six metres from the ground.
While the man was wearing the harness at times, he removed it and climbed to the top of the conjoined ladders.
The top ladder slipped, causing him to fall onto the balcony roof and slide off before falling to the ground.
The victim sustained a spinal injury, leaving him paraplegic for the rest of his life.
He also suffered a brain injury but this showed "gradual resolution".
In court, prosecutor Sofia Janackovic said Allred was to be sentenced on the basis he failed to provide supervision, instruction and training to the workers.
"June 9 was not an isolated or out of the blue incident," she argued.
"The risk [of falling from heights] was known throughout the industry but also by the defendant himself."
Barrister Steven Whybrow argued Allred's failures had been in instruction and supervision, "not some direction to undertake what was an extraordinarily foolhardy and unsafe activity".
"He would not in a million years, or at least his 64 years, have allowed someone to use a strap to tie two ladders together," Mr Whybrow said.
In lieu of a hefty fine, Chief Magistrate Lorraine Walker adjourned the matter to allow Allred the opportunity to cooperate with WorkSafe ACT.
She said this would allow time for Allred to create a safety video outlining his experience for training purposes. Allred is scheduled to face court again on December 19.
