Western Australian Police Minister Liza Harvey has defended a police decision to issue a $500 fine to an Aboriginal woman for stealing a box of tampons in WA's Goldfields.

The fine was issued under WA's new Criminal Code infringement notice system for the theft of the tampons, worth $6.75, from a Caltex service station in Coolgardie.

Ms Harvey said the system, which was introduced earlier this year, allowed people to avoid going to court and getting criminal convictions.

"Stealing of any kind is a serious offence which the community has no tolerance for and this Government doesn't apologise for handing out swift punishment of actual consequence," she said in a statement.

"Criminal Code Infringement Notices are in effect swift justice, save court time and allow police to continue frontline duties.

"Like all legislation it will be reviewed and monitored to ensure there have not been any unintended consequences."

The fines are issued at the discretion of police, but Law Society president Elizabeth Needham said it was not clear what discretion Coolgardie police had exercised in this case.

"The Law Society supports the use of infringement notices rather than the arrest and conviction process, because it can have some great benefits for the community and for an individual who then doesn't end up with a conviction and a long process of going through a court," she said.

"[But] discretion needs to be properly exercised.

"We don't know whether they used their discretion and if they did, what they took into account.

"We'd need to know why they ruled out cautioning the person as opposed to issuing the notice."

Police would not comment on the case.