Wearing body Armour for personal safety?

Hello, My friend in a not so jolly part of Flint, MI is a pharmacist and his DM refuses to agree to his requests to put up safety bullet proof glass in the pharmacy. He has been robbed twice in the last year in the store. He wants to start wearing Kevlar chest body armor under his employee uniform. Is this allowed? Any tips for staying safe in warzone-like areas? He has put up a sign that he printed on a 8.5 x 11 piece of paper that says "No hats, hoods or caps!" and immediately will yell... Wearing body Armour for personal safety?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums