This article clarifies the current state of affairs in Massachusetts: http://www.boston.com/news/local/massachusetts/articles/2010/01/12/police_fight_cellphone

This article clarifies the current state of affairs in Massachusetts: http://www.boston.com/news/local/massachusetts/articles/2010/01/12/police_fight_cellphone_recordings/ http://www.boston.com/news/local/massachusetts/articles/2010... The key seems to be how evident it is that the person is recording. If it is at all not obvious to the police that a recording is being made, it is illegal. If you put a microphone or camera in their face however it is OK.