Lawyers for Crown Casino have rejected claims the company has engaged in misleading and deceptive conduct through the use of "rigged" poker machines.

On day two of a civil case in the Federal Court, the company said the poker machines on the floor of its Melbourne casino were all approved by state regulators.

"We are doing nothing more than make authorised machines available," Neil Young QC told Justice Debbie Mortimer.

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The landmark case began on Tuesday, with lawyers for former gambling addict Shonica Guy seeking to prove that some poker machines are misleading and deceiving players.

Her action is against Crown Casino as well as Aristocrat, the manufacturer of the Dolphin Treasure poker machine.

Her lawyers are focused on that particular game, which they allege has a number of design elements that misrepresent the chances of winning.

They say it uses light, sound and image displays to fool gamblers into thinking they have won when they have in fact lost money.

Details were also given on Tuesday about an "oversized" fifth reel which has more symbols than the first four reels of the Dolphin Treasure game, reducing the chances of the symbols lining up and therefore decreasing the chance of winning.

There are 38 Dolphin Treasure games among the 1,080 Aristocrat brand poker machines on the floor of the Crown Casino in Melbourne.

Crown Casino said the machines were tested and approved by the Victorian Commission for Gambling and Liquor Regulation.

The company refuted claims made on Tuesday that Aristocrat was "kept informed of the performance of the machines" and had an "ongoing involvement with Crown".

Australian Baptist minister Tim Costello said poker machines were designed to be addictive. ( AAP: Joe Castro )

Mr Young said that Crown reported average turnover of the machines to Aristocrat "usually on a monthly basis".

"There is no other data exchange," Mr Young said.

He also said light, sound and image controls were regulated and beyond Crown's control.

"Crown is merely passing on the authorised software emanations," Mr Young said.

"The only thing Crown can control is to adjust the volume."

"We have the right under Victorian law to make the machines available because every feature has been authorised and approved," he said.

Outside the court on Tuesday, anti-gambling campaigner Tim Costello said it was about recognising that the poker machine was the problem, not individuals.

"It's the machine. It's designed for addiction, it's built for addiction. This case will show that, we believe, it's misleading, it's deceptive, it's rigged."

Ms Guy started gambling when she was 17 and spent 14 years struggling with addiction.

Aristocrat is expected to outline details of its case tomorrow.