In Samaroo v. Monasa case, the court held that where a payor’s underemployment or unemployment was a result of his or her actions (an event over which the payor had some control) or misconduct, the support obligations will not be reduced or cancelled. If the payor suffered from some medical ailment, then detailed medical opinion should be provided to satisfy the court that he or she was unable to work. Further, payor must make reasonable efforts to address whatever medical limitations they may have to earn income by following medical recommendations.
http://www.canlii.org/en/on/oncj/doc/2016/2016oncj47/2016oncj47.html