Law Times has released a video and an article considering the question. Bottom line: be part of a self-regulating body and carry a professional designation.
http://www.lawtimesnews.com/201704176086/focus-on/focus-mediators-largely-unregulated-in-canada
http://www.lawtimesnews.com/201704176100/videos/should-mediators-be-regulated?utm_term=Video%3A%20Should%20mediators%20be%20regulated&utm_campaign=CLNewswire_20170417&utm_content=email&utm_source=Act-On+Software&utm_medium=email