The Federal Court case was brought by Maurice Blackburn lawyers on behalf of gambling addict Shonica Guy, who suffered significant losses playing the machines.
"I started playing the pokies when I was 17. Poker machines took over my life for the next 14 years," she said.
"This case is not about seeking compensation for what I lost -- I just want to make sure what happened to me doesn't happen to anyone else."
Gambling addiction is a major social problem in Australia with advocates for reform estimating that people lose around USD 9.6 billion a year, with losses spiralling since the first machines were built in 1953.
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The legal case centres on the design of the "Dolphin Treasure" machines at Crown's flagship Melbourne casino, which offer cash prizes to players who line up matching symbols across a series of spinning reels.
It claims that the true chances of winning are misrepresented, with four of the reels the same or similar size, with around 30 symbols, but a longer fifth reel, which has 44.
This means it is much harder to land on the best symbols and get the highest prizes with a match on the last reel, the court heard.
"This is a landmark pro-bono action that we hope will shine a light on what we believe are grossly unfair practices within the poker machine industry," said Maurice Blackburn's Jennifer Kanis.
"The gambling industry is well aware of the research outlining the harmful effects of problem gambling on vulnerable people, and they have been for many years.
"Our concern is that despite these known risks, the industry continues to exploit vulnerable problem gamblers, by knowingly designing machines that are misleading and deceptive."
Aristocrat also "emphatically rejects any suggestion that its games are designed to encourage problem gambling, or in any way fail to comply with all relevant regulations and laws".
Guy is seeking an injunction banning Crown from operating Dolphin Treasure or any machine with a similar configuration, and for Aristocrat to stop supplying them.
The Alliance for Gambling Reform said although Guy might be the sole plaintiff, she was representing thousands of Australians.
"This trial can't come soon enough -- it should have happened years ago to mitigate the enormous harm which is imposed on communities year after year by a rich, powerful and well connected industry," alliance director Allison Keogh said.