Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 100A, § 7

Every registered motor vehicle repair shop and registered motor vehicle glass repair shop shall publicly display in its place of business its current certificate of registration. No unregistered motor vehicle repair shop or unregistered motor vehicle glass repair shop shall display in its place of business any certificate of registration or copy or facsimile of a certificate of registration, nor shall it in any manner state that it is, or hold itself out to be, a registered motor vehicle repair shop or a registered motor vehicle glass repair shop.