Massachusetts General Laws Part II. Real and Personal Property and Domestic Relations (Ch. 183-210) Ch. 186, § 1A

If land is demised for the term of 100 years or more, the term shall, so long as 50 years thereof remain unexpired, be regarded as an estate in fee simple as to everything concerning the descent and devise thereof upon the decease of the owner, the sale thereof by personal representatives, guardians, conservators or trustees, the levy of execution thereon and the redemption thereof if mortgaged or taken on execution.  Whoever holds as lessee or assignee under such a lease shall, so long as 50 years of the term remain unexpired, be regarded as a freeholder for all purposes.