The union behind a website that allows workers to review their employers says it is a step towards improving working conditions, but a legal expert warns it could produce a defamation headache.

Rate My Boss is a website funded by United Voice that allows users to share their experiences and frustrations relating to their employers in the hospitality industry and give them a rating out of five stars.

While some reviews praise employers for being "caring and respectful" and providing a "motivational place to work", others raise potential issues of defamation.

One anonymous review of a Ballarat restaurant said "dodgy accounting and under the table deals with local authorities keep this place in business. Chronic underpayment of staff wages".

"I feel sorry for the poor kids who work there, some for as little as $10 an hour," the review said.

More than 1,000 reviews had been uploaded to the website since it was established in December 2017.

Website 'empowers hospitality workers', union says

Brett Edgington is the secretary of the Ballarat Trades and Labour Council, an affiliate of United Voice, and has been overseeing the rollout of Rate My Boss in the Victorian city.

Mr Edgington said the anonymous reviews displayed on the website were moderated, and users had to log in through their social media profiles.

"When somebody leaves a comment on their website, they need to identify themselves to the website moderators," he said.

"So obviously if there are articles that are clearly defamatory then they're taken down."

Mr Edgington said common problems for hospitality workers included bullying, cash-in-hand payments, and non-payment of superannuation, overtime and penalty rates.

"This is a group of people in hospitality especially that are mainly casuals or employed cash-in-hand without an employment contract, and they've really been quite powerless in the past," he said.

"So if they raise an issue with their boss about payment or conditions, often that leads to termination instantly.

"This is a tool that empowers workers in that industry to … have a look at the website and seek employment with bosses that are rated highly, but also talk about issues that may have affected them."

Mr Edgington said that while "people have fake profiles on social media so occasionally some of those bosses come through" and review their own businesses, Rate My Boss could still provide reliable information.

"The more ratings you get on there, the more of a picture starts to build up and the more accurate that data becomes."

When does a bad review become defamation?

University of Western Australia law school senior lecturer Michael Douglas said Rate My Boss presented the potential for defamation, as did many online platforms.

"In order for a bad review to justify successful action, the review has to be substantially false," he said.

"So your rating will be defamatory if it disparages your boss, or causes other people to dislike him or her, or ridicule him or her, or to subject them to contempt.

"Even if you talk badly about a boss, even if you're justified in talking badly, there's potential for the boss to come after you with defamation law, but it's another question whether the boss will succeed."

Mr Douglas said if a review was defamatory, the employer could potentially sue Rate My Boss and the individual who wrote the review, if the business was small enough for him or her to be personally identified.

"But a practical difficulty in going after an individual who posted the review is that sometimes people don't identify themselves on the internet," he said.

"So for practical purposes it may be strategically desirable for Rate My Boss itself to be subject to defamation proceedings."

Mr Douglas said it was unclear whether the employer would be able to successfully sue Rate My Boss to access the reviewer's log-in information in order to identify them.

MP calls for government intervention

Liberal Member for Western Victoria Joshua Morris has called on the State Government "to either make sure that this website is fair or take it down".

"If there's no clarity of information, there's no transparency about who's posting on this website, it may not be fair and indeed the intent of this website is not clear either," Mr Morris said.

"There's data collection that's occurring here but it's also a fundraising website from the union, which is a distinct lack of clarity as well."

Users are given the opportunity to donate money to Rate My Boss on the website.

In a written statement, Victoria's Minister for Industrial Relations Natalie Hutchins said the Government was aware of the Rate My Boss website and had no regulatory responsibility for the website's content.

A spokesman for the Australian Hotels Association declined to comment.