With a few exceptions, parents who are going through a divorce, have as one of their top priorities, the welfare and best interests of their children. When disputes arise between parents it is often a result of a disagreement about what arrangement will best serve the needs and interests of the children and breakdown of how those needs and interest should be funded.
For example while both divorcing parents might agree that a child should go to summer camp, they may each think that the other should bear a larger share of the cost. Child support disputes may focus on the veracity of the reported incomes of each party, whether a departure from Wisconsin's standards is warranted. Once a child support order is in place there may, in some cases be an additional challenge surrounding enforcement.
Especially in the current economy there are certainly cases where despite the best efforts of the noncustodial parent they are no longer to satisfy the original child support obligation payments. Instances in which a substantial change in circumstances has occurred, a consideration of a modification in child support payments may be appropriate.
In addition to the cases in which a noncustodial parent is unable to pay despite their best efforts, there are those few cases in which a non-custodial parent actively seeks to avoid paying child support. This may be a result of simple greed, or an attempt to exact revenge on an ex spouse. In general enforcement is handled in state courts, though the federal government has recently created a website to assist with child support enforcement once the situation has passed into their jurisdiction.
Source: Office of the Inspector General, "Child Support Enforcement," Jan. 17, 2012