The largest union representing federal public servants is now formally urging Prime Minister Justin Trudeau to call a public inquiry into the Phoenix payroll system failure.

This week, Chris Aylward, president of the Public Service Alliance of Canada, sent a letter to the prime minister, explaining that previous investigations and reports — including the two audits completed by auditor general, Michael Ferguson — have not gone far enough.

Ferguson's spring report raised concerns about an "obedient" public service culture that fears speaking truth to power and so hesitated to bring up concerns with the Phoenix system, which Ferguson called an "incomprehensible failure."

For more than two years federal workers have been improperly paid by the system. Phoenix is so far set to cost the government more than a billion dollars and will eventually need to be replaced.

AG report too narrow in scope, union says

Aylward notes Ferguson looked at the lead up to the launch of Phoenix, but did not examine the events leading to the centralization of the pay centre or events after Phoenix was implemented.

"At some point in the project it was determined that 550 staff in Miramichi plus a new computer program could do the work of 1,200 staff and the old system — but how this conclusion was reached remains a mystery," Aylward said.

For instance, it wasn't until Radio-Canada and CBC reported on an early Phoenix business case that PSAC realize the project was set up without proper risk analysis, Aylward said.

Michael Wernick, Clerk of the Privy Council and Canada's top bureaucrat, criticized the auditor general's findings on Phoenix as 'sweeping generalizations.' (Julie Ireton/CBC)

Top bureaucrat dismisses report as 'opinion piece'

Earlier this week that Canada's top bureaucrat, Michael Wernick, called the auditor general's report on Phoenix an "opinion piece."

Wernick, the clerk of the privy council, told members of the House of Commons public accounts committee Tuesday Ferguson's findings were "sweeping generalizations."

Aylward said it is disappointing to hear a senior public servant dismiss a scathing report from an auditor general.

"It's clear without additional investigation and a public inquiry, there's a need for real change and unfortunately that change right now is not going to be accepted by senior bureaucracy — either by the prime minister's office by the sounds of it — or the clerk of the privy council," Aylward said.

A public inquiry would also provide a public forum for witness testimony and evidence, allowing his members to speak out about the impacts of the Phoenix failure, he said.

​When asked in Question Period on May 29 if the government would launch a public inquiry into Phoenix, Public Services and Procurement Minister Carla Qualtrough said that after several studies and audits dissecting Phoenix, the government knows very clearly what happened, and laid the blame with the former Conservative government.

"I very strongly believe that the former Conservative [government] set this project to fail," Qualtrough said in a later interview that day.