Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 140, § 141D

(a) No person shall sell, offer to sell, exchange, trade, barter, lease or transfer any dog or cat on any roadside, public right-of-way, parkway, median, park or other recreation area, flea market or other outdoor market or commercial or retail parking lot.

(b) This section shall not apply to the: (i) transfer, regardless of payment or compensation, of a dog or cat by or to a shelter or animal rescue organization licensed pursuant to section 39A of chapter 129 or a municipal animal control facility; or (ii) display of a dog or cat as part of a state or county fair exhibition, a 4-H program or similar exhibition or educational program.

(c) A violation of this section shall be punished by a fine of not more than $50 for a first offense, a fine of not more than $100 for a second offense and a fine of not more than $300 for each subsequent offense. Each dog or cat sold, offered to be sold, exchanged, traded, bartered, leased or transferred in violation of this section shall constitute a separate offense.

(d) A city or town shall enforce this section through its animal control officers or police officers in a manner consistent with the disposition provisions in section 21D of chapter 40.