What if my ex-spouse believes that child support is unconstitutional, and refuses to pay?

There is no argument. Child support has never been held to be unconstitutional, under either federal or any state’s constitution. In fact, willful failure to pay child support is a crime in every state.

In some states, failure to pay is a misdemeanor, in others, it is felony. If he or she fails to pay child support you will be subject to fines or imprisonment, or both. Courts don’t like to send parents to jail for failure to pay child support, since this would usually cut off the parent’s ability to pay and visitation, but it has been done in egregious cases.