Former prime minister Kevin Rudd is due to give evidence from New York as part of a class action in Melbourne over his government's pink batts scheme.
Mr Rudd will give sworn evidence via video link to the Victorian Supreme Court on Monday.
The court in May ordered Mr Rudd to give evidence in the case, which began in late April.
The class action over the abrupt cancellation in 2010 of the Rudd government's home insulation program is seeking about $150 million in damages from the Commonwealth of Australia.
More than 140 businesses have joined the class action, which claims they suffered heavy losses when the program was shut down for safety reasons as a result of the government's negligence.
The Rudd government established the $2.7 billion Home Insulation Program in 2009 as part of a broader $42 billion economic stimulus package.
But it was shut down a year later following the deaths of four workers in NSW and Queensland in 2009 and 2010.
When the case opened on April 23, class action barrister Jim Delany QC said the market for retrofitting homes with insulation totalled less than 70,000 homes annually before the scheme.
The program promised to fit 2.2 million homes over a two-year period, representing about a 15-fold increase in demand.
The class action says businesses took on staff, expanded production and invested in new machinery and other equipment to meet demand.