leving and father's rights activist glenn sacks have argued that parenting time interference can result from the custodial parent's relocation beyond a practical distance from the noncustodial parent, and have campaigned for a rebuttable presumption prohibiting such relocations. in 1985, leving helped draft the illinois joint custody law, allowing judges to assign divorcing parents equal responsibility for raising their children. leving worked for its passage in the illinois general assembly, and "is credited with generating much of the pressure that got the bill passed". by 1991, leving was described as "one of the most recognizable names among chicago lawyers".