I don't recall that incident with the Mass State Police. How recent was it?
During the second Dukakis administration, the Massachusetts State Police would stake out the New Hampshire State Liquor Store, which was conveniently located in the median of the Interstate.
When Massachusetts residents would return to Massachusetts, the State Police would arrested them for failure to pay tax on the Liquor.
After the New Hampshire State Police arrested the Massachusetts State Police officers for loitering, the practice finally came to an end.