Mass. Gen. Laws ch. 271 § 21
In a prosecution or proceeding relative to lotteries, policy lotteries or policy, buying and selling pools or registered bets, any words, figures or characters, written, printed or exposed upon a blackboard, placard or otherwise, in a place alleged to be used or occupied for such business, purporting or appearing to be a name of a horse or jockey, or a description of or reference to a trial or contest of skill, speed or endurance of man, beast, bird or machine, or game, competition, political nomination, appointment or election, or other act or event, or any odds, bet, combination bet or other stake or wager, or any code, cipher or substitute therefor, shall be prima facie evidence of the existence of the race, game, contest or other act or event so purporting or appearing to be referred to, and that such place is kept or occupied for gaming; and in all cases the same may be proved by a copy or by oral description thereof.
Mass. Gen. Laws ch. 271, § 21