Hills Labor councillors believe their Liberal counterparts should be watched very closely now a new code of conduct bans party members being bound to a vote.
The code of conduct for all NSW councils came in to effect on March 1.
Labor councillor Tony Hay said it had been commonplace for both parties to form binding votes in the past — but that practise was now outlawed.
Cr Hay said extra scrutiny was needed on the nine Liberal councillors, who had almost always voted as a party since the September election.
"They don't call it a caucus but they form a position through their party room meetings," he said.
"When you see a block vote of nine to three you have to question whether there's been a binding position made in the Liberal Party room."
The code of conduct also puts tough but broad conditions on councillors who may bring the council "into disrepute". His Labor colleague, Cr Raymond Harty, said the powers were far too broad and could be used to gag councillors.
"I think it is a way of effectively gagging dissenting voices," he said.
"If I speak out against something, am I going to be deemed a disreputable influence in the council?"
Liberal mayor Michelle Byrne refused to answer questions about whether Liberal councillors could use the code to gag Labor voices in the chamber.