Moves to grant rank-and-file members of the WA Labor Party more power in pre- selecting candidates will not be extended to a number of smaller branches.
Opposition Leader Mark McGowan hailed as "historic" yesterday reforms that would give lay party members a 50-50 say - alongside caucus - on choosing State Labor leader.
He also touted changes to the preselection process that will give branches in some seats significantly more sway in determining which candidates go to an election.
Combined with moves to toughen up on branch stacking, the new rules bring the party closer into line with its Federal counterpart.
However, Mr McGowan later acknowledged the new preselection arrangements would not apply to all seats because some were deemed to have too few members.
Under the reforms, Lower House electorates in which there are more than 60 party members will get a 50 per cent say in preselecting candidates, with the remaining weighting to be decided by its State executive.
In electorates where there are between 40 and 60 Labor members, branches will have a 25 per cent say in preselections.
Members would need to have been a member of the party for at least 12 months before they can vote.
The reform goes further than some observers had feared, after suggestions local participation would be restricted to electorates of more than 80 members, meaning hardly any seats would have been eligible.
Mr McGowan said 32 seats had more than 60 members, and a further 17 had between 40 and 60, meaning lay party members in just 10 seats would not have a say in preselections under the new rules.
In the Upper House, regions would need to boast a minimum of 200 Labor members before they could have a 25 per cent say in preselecting candidates.
Mr McGowan said he hoped the rules, which he lobbied hard to secure, would lead to an increase in the party's membership and empower more of the branches.
The preselection process for the 2017 State election is due to start in about 18 months.
"These are the biggest democratic reforms to the WA Labor Party in its history," Mr McGowan said. "Party membership will be more meaningful and relevant."