What is the test for reducing or cancelling a parent's child support arrears?

This court has considered the principles to be applied in Earle v. Earle, cited above. The principle that parents have a joint and ongoing responsibility to support their children, based not just on what they earn, but on their earning capacity, applies to the question of arrears. At para. 27 the court said that it is not good enough just to say that a parent could not pay because he or she earned less. The parent can only obtain a reduction or a cancellation of arrears if he or she presents detailed and full financial disclosure under oath that: i. the change was significant and long lasting and, ii. the change was real and not one of choice and, iii. every effort was made to earn money (or more money) during the time in question, and those efforts were not successful.