7-19-16 Honda of Westport Couple's court: Should they put their child on a leash to keep him close?

Their three-year-old has a history of running off, and she wants to keep him on a leash to make sure he is always be her side. Her boyfriend is not fond of the idea, however, and thinks it won't teach his son any discipline/ Should they strap in their child or let him run loose?