SYDNEY (AFP) - An Australian academic has braved the wrath of millions of his compatriots in an attempt to stop the government giving them hundreds of dollars each and urging them to go shopping.

The cash handouts are part of a 42 billion Australian dollar (S$42 billion) economic stimulus package designed to kick-start the flagging economy amid the global financial crisis.

More than seven million taxpayers who declared earnings of less than 100,000 Australian dollars last year are due to start getting payments of up to A$900 each in the mail or in their bank accounts this week.

Prime Minister Kevin Rudd calls the payments a "tax bonus", but law lecturer Bryan Pape was due to challenge the plan in court Monday, saying it is unconstitutional.

"Bryan Pape is trying very hard to be the most unpopular man in Australia," wrote Sydney Morning Herald columnist Tim Dick under the headline: "Mission to stop the manna from Kevin".

Like many millions of other Australians who are delighted at the idea of being handed 900 dollars and being told it is their patriotic duty to spend it, Dick wants Pape to lose his case.

Pape, who lectures at the University of New England, says calling the payments a tax bonus is false.

"Saying so doesn't make it so, and the first question will be -- is it a law with respect to taxation?" he told ABC radio ahead of the case. "I say it is not. I say it is a gift."

Pape is a former local official in the conservative rural-based National Party but says he is not acting politically to kill what the opposition has dubbed the centre-left government's "cash splash".

Instead, he says he is testing arguments he raised in a 2005 academic paper, in which he claimed the government was misusing its appropriations powers.

Millions of Australians will be hoping that the High Court judges, who have set aside two days for the case, give him a failing grade.