Separate shelves for eggs which are truly free-range would make shopping easier for consumers, the Greens in South Australia say, as they launch a second private member's bill to legislate the standards.

The bill, introduced by the Greens' Tammy Franks, outlines that cartons of eggs should be displayed separately under labels 'free-range', 'barn eggs' and 'cage eggs'.

Attempts to legislate standards for free-range eggs have so far failed to achieve a uniform approach.

Consumer advocacy group Choice recently investigated 55 products and found a lack of consistency in how free-range eggs were defined.

It said companies were cashing in on consumers wanting to buy ethically but the absence of a national standard meant use of the term 'free-range' became meaningless.

"Consumers are being dudded and it's time to crack the free-range egg rort," Ms Franks said of her SA legislation.

"This bill seeks to crack the problem in a very simple way and it's a way that's worked in the ACT since 2001."

Ms Franks said proposed shelf labelling would be based on a national animal welfare code of practice, which required no more than 1,500 hens per hectare for the term free-range to apply.

"While we haven't been able to get an agreement on making sure if it says free-range on the carton that it's free-range inside the carton, I'm hoping that all parties will now come together and say 'if it's on a South Australian retail shelf, if it says free-range on the shelf, it's free-range in the carton'," she said.

The Greens MLC said her previous bid to legislate a free-range standard was opposed by the South Australian Government, which cited cross-border trade issues.

She said the SA Government had since introduced a voluntary code which specified a limit of 1,500 hens per hectare, so it should now support her latest legislative attempt.

The Greens-sponsored bill would allow fines of up to $5,000 for failure to comply with free-range standards, and is likely to be voted on before the end of the year.