The Boston Sunday Globe reported on  a recent decision (and included a link to the opinion) by Superior Court Judge Douglas Wilkins that arrest records and mug shots are not exempt from Freedom of Information laws.  The police departments involved may appeal to get a firm answer on the extent of their obligation to open their files to the press and public.

https://www.bostonglobe.com/metro/2017/12/08/judge-mug-shots-arrest-reports-officials-are-public-massachusetts/rqfdo2j7oySo1kG2Vd3ABI/story.html

Social Law Library resources on state and federal freedom of information law include:

Public Records and Open Meeting Law  http://encore.socialaw.com/iii/encore/record/C__Rb1145122

Freedom of Information and Public Records Law in Massachusetts  http://encore.socialaw.com/iii/encore/record/C__Rb1141243

The Federal Information Manual  http://encore.socialaw.com/iii/encore/record/C__Rb1137172

Federal Information Disclosure  http://encore.socialaw.com/iii/encore/record/C__Rb1135371