The Maritime Union of Australia (MUA) has called moves to disendorse the Labor candidate in the Perth seat of Fremantle "an absolute disgrace and a nonsense".

Key points: Labor to meet today to disendorse Fremantle candidate Chris Brown

Labor to meet today to disendorse Fremantle candidate Chris Brown Mr Brown says he did not need to disclose convictions as they were "spent"

Mr Brown says he did not need to disclose convictions as they were "spent" Maritime Union says axing Mr brown is a "miscarriage of justice"

Maritime Union says axing Mr brown is a "miscarriage of justice" Issue likely to become a distraction on the federal election trail

Labor's national executive will meet today to disendorse MUA backed candidate Chris Brown, who did not disclose two convictions on his preselection paperwork.

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One was for assault during a fight involving several men, which led to a 12-month suspended sentence, and the other was for drink-driving.

Both offences date back to the 1980s when Mr Brown was 18 and 19.

"I'm a fine upstanding citizen that was caught up in a couple of these things when I was an 18, 19-year-old, and I've had no other issues or convictions since," Mr Brown told the ABC.

He said his lawyer advised him to plead guilty to the assault, but in fact he had been the victim.

"I wished I had of challenged it," he told the ABC.

"I was the victim of that assault."

In 2011 he successfully applied to have the conviction "spent".

He argued because of this, there was no requirement to list it on his preselection paperwork.

He also said he told a Labor Party official about it at a meeting four weeks ago.

"The question was asked 'is there anything in your history?' and I said, 'well, sure'.

"I've had these two instances, I don't hide from it, that's part of who I am, and I actually think I should be using them as a strength to show youth there's a positive way forward," Mr Brown said.

We're not all members of the Salvation Army: MUA

The MUA condemned Labor's move to disendorse Mr Brown over matters he was involved in 30 years ago as a teenager.

"On the waterfront by the way we're not all members of the Salvation Army, but I have got to say this is an absolute miscarriage of justice," MUA national president Christy Cain said.

He argued that because the assault conviction was spent, Mr Brown was correct not to tick a box on the preselection paperwork saying he had a conviction.

Mr Cain had warning of his own for the national executive.

"It is a crime actually to go out there and try and do what these people are trying to do to destroy Chris's credibility," he told AM.

Shorten backed Brown for preselection but doesn't support him

Opposition Leader Bill Shorten gave his backing to Mr Brown when he was Labor's preselection for Fremantle in March.

Mr Shorten talked about the importance of diversity in politics and having MPs to represent the interests of working people.

"The Labor Party of Fremantle has picked a small businessman, they picked someone who's lived in the local community, they picked someone who did reasonably well in the local ballot," Mr Shorten said at the National Press Club.

Now Mr Shorten has thrown his support behind Josh Wilson, the Deputy Mayor of Fremantle, who won more votes in the preselection ballot at a local level, but lost to Mr Brown because he had the backing of the Maritime Union at the state council.

The issue is likely to be a distraction on the campaign trail that Mr Shorten does not need, and it fits neatly with the Coalition attack on Labor and the unions over violence and lawlessness exposed at the royal commission into trade unions.