A former head of the Criminal Bar Association is astounded the goalposts have seemingly changed in David Bain's bid for compensation.

LISTEN ABOVE: Gary Gotlieb speaks to Rachel Smalley on KPMG Early Edition

A report by retired Australian judge Ian Callinan QC, has found Mr Bain does not meet a threshold of innocent beyond reasonable doubt.

But former Criminal Bar Association President Gary Gotlieb told Rachel Smalley that test is nowhere in the Cabinet rules around compensation.

FULL STORY: Major blow for Bain's compensation claim

He said someone must prove they're innocent on the balance of probabilities, "and that's a pretty strong test."

"To up it to this innocent beyond reasonable doubt is virtually impossible. It's such a discretionary thing."

"Now where this beyond reasonable doubt comes about, I'm absolutely lost. Because that is not the test that has been for as long as I can remember."