The Archeological Resources Preservation Act, or ARPA, is the grand-daddy of the laws that protect artifacts. You need to understand what ARPA is.
There is also another law that follows on the heels of ARPA. The National Historic Preservation Act.
Basically, if you are detecting in Massachusetts, on State Lands, do not dig any item that you believe is older than 100 years. If you want to detect on private property, then be sure you get written permission from the landowner.
This Massachusetts regulation governs the use of metal detectors on State Forests and Parks property:
“No Person shall use or offer to use metal detectors on Department property except at the discretion of the area Supervisor on designated swimming beaches and designated campsites. The Director may issue a special use permit authorizing archaeologically-related or geologically related activities.”
Metal detecting is allowed on beach and campsite areas with permission of the Park Supervisor.
If you want to detect in Massachusetts town, village and city parks, you'll need to check with those local officials. Each of these have their own rules, laws, or ordinances. There are also
Do not let the laws scare you from enjoying the hobby.
If you are a metal detectorist, or you are thinking of beginning the hobby, but afraid of all the laws and restrictions against the hobby, do not give into the beauracracy. If you do quit, that means the lawmakers win.