The Court of Appeal ruled that regulations underpinning the Government's "back-to-work" schemes were legally flawed.
Judges Lord Justice Pill, Lady Justice Black and Sir Stanley Burnton unanimously agreed in a judgment in February this year that the 2011 "work for your benefits" regulations failed to give the unemployed enough information, especially about the sanctions for refusing jobs under the schemes.
The ruling was a victory for university graduate Cait Reilly, 24, from Birmingham, who challenged having to work for free at a local Poundland discount store.
It was also a victory for 40-year-old unemployed HGV driver Jamieson Wilson, from Nottingham, who objected to doing unpaid work cleaning furniture and as a result was stripped of his jobseeker's allowance for six months.
The UK's Supreme Court is set to rule today on the legality of the Government's "back-to-work" schemes at the centre of the high-profile Poundland case.
Work and Pensions Secretary Iain Duncan Smith is attempting to overturn a Court of Appeal ruling that regulations underpinning the schemes were legally flawed.
The schemes were condemned by critics as ''slave labour'' because they involved work without pay and cuts in jobseeker's allowance for those who failed to comply with the rules.
University graduate Cait Reilly, 24, from Birmingham, and 40-year-old unemployed HGV driver Jamieson Wilson, from Nottingham, had both succeeded in their claims that the unpaid schemes were legally flawed.
The work and pensions secretary has criticised people "who think they're too good" to stack supermarket shelves. Iain Duncan Smith said many "smart people" overlooked the importance of effective shelf-stacking.
He said: "I understand she said she wasn't paid. She was paid jobseeker's allowance, by the taxpayer, to do this. I'm sorry, but there is a group of people out there who think they're too good for this kind of stuff."
"Let me remind you that [former Tesco chief executive] Terry Leahy started his life stacking shelves."
The next time somebody goes in - those smart people who say there's something wrong with this - they go into their supermarket, ask themselves this simple question.
"When they can't find the food they want on the shelves, who is more important - them, the geologist, or the person who stacked the shelves?"