"The self-interested pursuit by union officials of factional power as a pathway to elected office invariably trumps any bid to democratise the party or empower the membership," he writes in an opinion piece.

His salvo coincides – albeit unintentionally – with Saturday's annual conference of the ACT branch, where 327 delegates meet to debate party rules.

Mr Stanhope is a longtime critic of the factions, but his latest intervention was prompted by his anger over the party's about-turn on asylum seeker boats, its treatment of Norfolk Island, and its attitude to the royal commission on trade unions.

He said just four of the 397 delegates to the recent national conference did not belong to a faction, leaving half or more of the wider party membership virtually unrepresented, and the stranglehold of the unions and factions meant democratic changes were stifled.

Mr Stanhope said on Friday he hadn't intended his criticism to coincide with the ACT branch conference, and the ACT branch was a "standout" as the most democratic branch of the party by far, with full rank and file preselection of candidates, among other measures.

But he said the ACT conference should be open to all 1700 members, not only to the 327 delegates – of which 145 represent unions, 145 represent sub-branches and the rest are made up mainly of parliamentarians and the administrative committee.

"If an organisation like BHP with 50,000 shareholders can have an annual shareholders' meeting which everybody can attend then the ACT Labor Party doesn't need to exclude anybody from its conference," Mr Stanhope said.

"[But ] anybody in the Labor Party knows the reason why that sort of idea would meet resistance is that it completely disempowers the factions and it empowers the membership."

Labor secretary Matt Byrne said he did not know how many of today's delegates were members of factions.

Mr Stanhope said the party "simply has to get its head out of the sand" and begin addressing systemic problems if it was not to repeat the failure of the Rudd Gillard years which left many convinced it was incapable of governing.

"I look on in horror at the behaviour of my federal colleagues over those six years and I believe that what shone through during that period was the extent to which the factions, which are driven by the unions, were responsible," he said.

While the royal commission was an "appalling and cynical political exercise" on the part of the Abbott government, it was nevertheless "the witch-hunt we had to have", shining a light on deep-seated problems.

"I don't disagree for one minute that the royal commission is an outrageous abuse of political power and an outrageous political exercise but it's a reality and it would be a pity if the lessons that are there to be learned for the Labor Party aren't taken on board," he said.

Allegations in the commission went to the heart of Labor's integrity, he said, pointing to the convictions of former Health Services Union bosses Michael Williamson and Kathy Jackson, both of whom were senior Labor Party figures.

In Canberra, a former Construction, Forestry, Mining and Energy Union official Halafihi Kivalu has pleaded not guilty to two counts of blackmail. He was a former president of a Labor sub branch, and Mr Stanhope said the CFMEU was the most powerful and influential union in the left faction of the party by dint of its relative wealth as the effective owners of the Tradies clubs, its size and the strength and personality of its leadership.

While he expected the Labor party would continue to distance itself from allegations against the CFMEU, and other unions, it could not escape the link.

"The ALP will insist that it was "them" that were at fault, not "us", when in fact they are in reality "us"," he writes.