It is a basic and oft-cited principle of Massachusetts zoning law that the courts give "'some measure of deference' to the local board's interpretation of its own zoning by-law." Britton v. Zoning Bd. of Appeals of Gloucester, 59 Mass. App. Ct. 68, 73 (2003), quoting APT Asset Mgmt., Inc. v. Board of Appeals of Melrose, 50 Mass. App. Ct. 133, 138 (2000). The standard for this measure of deference, however, is tautological: the courts "accord deference to a local board's reasonable interpretation of its own zoning bylaw, with the caveat that an 'incorrect interpretation of a statute . . . is not entitled to deference.'" Shirley Wayside Ltd. Partnership v. Board of Appeals of Shirley, 461 Mass. 469, 475 (2012), quoting Atlanticare Med. Ctr. v. Commissioner of the Div. of Med. Assistance, 439 Mass. 1, 6 (2003) (citations omitted). Put differently, deference is given to a local bylaw interpretation when the courts happen to agree with that interpretation. This standard, as one might expect, is not completely conducive to predictable outcomes.