Politicians are breaking the law by putting up election posters prematurely, the South Australian Local Government Association says.

Liberal Member for Adelaide Rachel Sanderson already has posters up in her electorate, including in Prospect and Walkerville.

LGA chief executive officer Matt Pinegar said political parties were legally allowed to put up posters from 5:00pm, ahead of the writs being issued tomorrow.

"The rules are very clear, they must also be taken down 48 hours after the election," Mr Pinegar said.

"We've communicated this to all political parties, the guidelines are available on our website so they should not be up now."

Mr Pinegar said if candidates did not have permission from councils to erect the posters, councils could direct them to be removed or issue expiation fines up to $5,000.

Councils could also remove the posters themselves if they wished.

Voters should consider 'candidates' disregard for the law'

While the LGA would unlikely take action against candidates today, Mr Pinegar urged people to take candidates' disregard for the law into consideration when voting.

"I find it incredible that people who want to be members of parliament or continuous members of parliament think they can flout laws that are very clear and accessible, and ones that we've communicated to all political parties and candidates," Mr Pinegar said.

"I would encourage people to reflect on why they're seeing them [posters] before 5:00pm when all political parties know what the rules are, and perhaps take this into consideration when they vote."

A City of Prospect Council spokesperson said Ms Sanderson "had gone renegade on us" and not sought permission to erect the posters, nor had permission been granted.

Opposition spokesman Rob Lucas said any early erection of election posters just comes down to enthusiasm.

"I think what it indicates is how desperately keen candidates and Liberal Party supporters are to get rid of a very bad Weatherill Government after 16 years, so there's a little bit of enthusiasm there," Mr Lucas said.

"In the greater scheme of things, when we're talking about the scandal at Oakden, the debacle of child protection, the TAFE debacle as well, the issue of whether or not corflutes have been erected a few hours earlier on the day, I think probably for most people will be a lower order issue."