From Longman Business Dictionary
bylawby·law /ˈbaɪlɔː-lɒː/ (also byelaw) noun [countableC]1LAW a local government law that must be obeyed by the people living in an area, or people visiting ita bylaw banning public drinking in the town centre
2a rule made by a company or organization that must be obeyed by the people working for it