If the elements of the federal crime have been met and the non custodial parent can be charged for their failure to support the child(ren) then so should their spouse. Wives and husbands of a NCP that does not properly support the child(ren) from a previous relationship where there has been a court order established should be equally held accountable. A NCP that is working off the books or under the table to where a wage garnishment is impossible should not be allowed to live off/behind their spouse to avoid their court ordered obligation.
Holding a spouse potentially responsible would eliminate a NCP and the spouse from hiding assets in one another's name to avoid payments.