Experts say Sydney Lord Mayor Clover Moore may have a tough time in this weekend’s council election after controversial changes to voting rules.

The New South Wales Government changed the City of Sydney Act back in 2014 to force the enrolment of around 40,000 businesses in the Sydney local government area.

The changes effectively double the votes available for businesses and landlords, but not unions who own property.

Individual citizens still get only one vote.

Legal expert Bret Walker SC has warned there is a gap (a "lacuna") in the laws that means a company and a person, or several people, who own or occupy a business together, could get more votes.

“The lacuna, insofar as it operates in respect of the natural persons identified above, presents a very serious potential to exploit the electoral system for council elections by effectively allowing stacking of the non-residential rolls,” Mr Walker says.

“For example... an occupier of rateable land in the City of Sydney could incorporate a company which jointly occupies that premises. The first occupier could then invite, say, 10 friends to share his occupation of that premise[s].

“The joint occupiers could then elect not to nominate two natural person electors on their behalf. In those circumstances, each of the 11 natural person joint occupiers would be entitled to be enrolled,” he said.

The pro-business changes are seen as an attempt to boost the chances of Liberal mayoral nominee Christine Foster, but Dr Peter Chen from Sydney University's Department of Government and International relations says the assumption that business vote Liberal may not stand up.

“The simple assumption that all of the business electors will elect comparatively conservative or Liberal candidates, I don't think this necessarily is the case,” he told the ABC.

“A lot of the participants won't be the big end of town they'll actually be small [or] medium enterprises.”

Cr Moore agrees it may backfire.

“They can see it for what it is a gerrymander cobbled together by [former Liberal councillor] Edward Mandla and the Shooters Party, and enacted by the Baird Government,” she said.

“They can see all that and they're really angry about it, and I'm getting a lot of that feedback and a lot of support.”