When challenging the validity of a local zoning provision, "every presumption is to be made in favor of the provision and its validity will be upheld unless it is shown beyond reasonable doubt that it conflicts with the enabling act." Vagts v. Superintendent & Inspector of Buildings of Cambridge, 355 Mass. 711, 713, 247 N.E.2d 366 (1969), quoting Lanner v. Board of Appeal of Tewksbury, 348 Mass. 220, 228, 202 N.E.2d 777 (1964). Though reaffirming the heavy burden borne by a party challenging a zoning amendment, the Supreme Judicial Court recently commented that "the characterization of a challenger's burden as one of proof beyond reasonable doubt may not be instructive. A better characterization is that the challenger must prove by a preponderance of the evidence that the zoning regulation is arbitrary and unreasonable, or substantially unrelated to the public health, safety, morals, or general welfare." Johnson v. Edgartown, 425 Mass. 117, 121, 680 N.E.2d 37 (1997).