No. However, after inquiry, they have to be made clearly legible.

ADDED: Since all badges are issued by the government or agency to which the member belongs they are all uniform in size and legibility and, one would assume, meet the legal requirement for the wearer’s identification. HOWEVER: if the member knowingly and deliberately obscures the badge in any way (the exception being a mourning symbol across the badge) he should be reoported to a superior.