The Australian Lawyers Alliance said the successful prosecution against construction giant John Holland, which is overseen by the national safety regulator Comcare, has highlighted a series of failures.

Lawyers Alliance national president Andrew Stone said it emerged in a recent court case that John Holland had breached occupational health and safety laws several times before the successful prosecution. He said the company was fined $110,000 after a worker suffered a head laceration when a bridge at the Brisbane Airport Link site collapsed.

"Months earlier, a person on the same worksite was crushed to death. That case is yet to be resolved," Mr Stone said.

"It must be asked: where was Comcare in preventing these breaches?

"If Comcare is struggling to adequately regulate worker safety across only 33 companies, why on earth would you put more workers from across the country at risk by allowing employers to leave well-funded and well-administered state-based schemes to join Comcare's poorly functioning regulatory arrangements?".

Comcare covers national companies Australia Post, Telstra and the Commonwealth Bank. The federal government recently introduced legislation to expand Comcare's role to allow more businesses to enter the scheme.

Mr Stone said the government's plan to expand Comcare's workplace safety advisory role was a "disaster waiting to happen, given its demonstrated inability to regulate safety in the workplaces for which it is currently responsible".

"Sadly, it is cases like this that we continue to warn [federal Minister for Employment Eric] Abetz about, yet none of the three pieces of legislation introduced by the senator relating to Comcare address these deficiencies," Mr Stone said.

"Instead, Senator Abetz wants to further expand a poorly functioning scheme that has an appalling safety record and open up that scheme to even more businesses across the country."

Mr Stone said Comcare reported 13 workplace fatalities within its mandate in its annual report last year.

A spokesman for Mr Abetz said the successful prosecution demonstrated Comcare was doing a good job.

"The very fact that a prosecution was taken and successful shows that Comcare is an effective and active regulator," he said.

"The Australian Lawyers Alliance has an unfortunate history of defending the rorts and loopholes that currently exist in the Comcare scheme.

"It is disappointing that this body is putting the interests of those who would benefit from the current flaws in the scheme at the expense of taxpayers who fund the scheme."