Massachusetts Supreme Judicial Court January 6, 1915 (Security Bank of New York v. Callahan)

Braley, J.

While at common law not only the subject matter must be in existence and in the actual or potential possession of the assignor, but partial assignments are not recognized, a court of equity will protect and enforce such assignments by beneficiaries under trusts where the right has not been cut off by the testator, and by heirs and legatees of their contingent interest in funds or