One of the vexing issues of family law is whether to award "retroactive" child support. If child support awards don't include back payments, then children are being cheated -- if they do, then it is often difficult for the payor to meet them.
The Pithlord recognizes the need for payment schedules for lump sum back child support, but is otherwise unsympathetic to the payor. In Canada, child support levels are based on a prescribed schedule that depends on the payor parent's income (child support for unmarried parents is within provincial jurisdiction, but most provinces have adopted the same basic system). If your income goes up, you ought to be paying more. If your ass needs to get dragged into court, you shouldn't get the benefit of that.
I'm not particularly sympathetic to judicial discretion in this area, but I recognize that the statutes have retained it. Still, there needs to be some kind of "default rule."
On Monday, the SCC decided a number of related appeals on this issue. Everyone agreed on the disposition of the specific cases, and that there needs to be some discretion, but with a default rule. The court split on what that default rule should be.
Justice Abella, for the minority, thought the default should be to the date the payor parent got the higher income. That makes sense, since that's the date the payor should have been payin'.
The majority, on the other hand, makes the presumptive backdate when the payor got "effective notice" from the other parent. This makes less sense, since we usually know about our own raises before we find out about our exes'. Also, effective notice is a mushy concept, as is the kind of bad behaviour that would justify further backdating.