Last updated Feb 13 2006 09:09 AM MST

CBC News

The Supreme Court of Canada heard arguments on Monday from four Alberta fathers who are fighting child support rulings.

The case could have dramatic implications for the finances of divorced parents across the country.

The men were all told to make retroactive payments of up to $100,000 after the Alberta Court of Appeal ruled they should have disclosed they were making more money than they were when the support order was first issued.

Their Toronto lawyer, Deirdre Smith, has asked the top court to reverse that decision. She says the Alberta court overstepped federal rules.

She says there is nothing in federal law requiring the parent paying support to automatically inform the other parent when their income rises, and to increase payments.

She says that under the current system, the parent with custody can ask about changes in the other parent's income whenever they wish, and can also ask for an increase in child-support payments.

"The Alberta Court of Appeal really did take this whole area of law into a new scope and area by making this very strong suggestion that all support payers have a responsibility to annually provide financial disclosure whether it's requested or not, and more importantly to annually change the amount of child support they are paying whether the mom wants it or not," she told CBC News on Sunday.

Smith says she will argue that the Alberta Court of Appeal's ruling that these payments should be renegotiated once a year is not written into the federal law.

She says it would be best if families were given flexibility, rather than forcing them to open up custody agreements on an annual basis.

Meanwhile, Gus Sleiman of the Men's Educational Support Association in Calgary says it's not fair to ask for money after the fact.

"This is an unreasonable kind of expectation of a non-custodial parent to pay when at the time they have spent their money and they are under the presumption they already paid their child support," Sleiman told CBC News.

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