(concurring, with whom Quirico, J., joins). I concur with the result reached in the main opinion; the by-law amendment is invalid. I do not join in the reasoning of the main opinion. In my view it is not necessary here to apply the principles of Roe v. Wade and related cases. This court should adhere to the important maxim that it reaches constitutional challenges only when it is necessary to do so. It is not necessary here. I would *289hold that this by-law amendment is not valid as a matter of statutory construction.
I would hold that the authority to regulate specific requirements for health facilities, including the location of such facilities, has been delegated by the Legislature to the Department of Public Health. G. L. c. 111, §§ 25C, 51, 51A. The local by-law is not controlling since it conflicts with the scheme of the general law. See Bloom v. Worcester, 363 Mass. 136, 149 (1973). Cf. New England LNG Co. v. Fall River, 368 Mass. 259, 267 (1975). This is true because, although the Department of Public Health was in the process of approving the facility, the effect of the by-law is to exclude such clinics altogether; there would be no conflict, of course, if the by-law imposed reasonable regulation as to location within the town.
Further, I would hold that the by-law cannot be upheld within the meaning of the enabling zoning statutes, G. L. c. 40A, §§ 2, 3. It is true that every presumption will be made in favor of a zoning amendment unless it is shown beyond a reasonable doubt to conflict with the enabling act. Lanner v. Board of Appeal of Tewksbury, 348 Mass. 220, 228 (1964). Aronson v. Sharon, 346 Mass. 598, 603 (1964). Nevertheless, the by-law here does not pass muster under the statutes. The by-law would permit all medical clinics except abortion clinics to operate in the area zoned for industrial uses. Under the enabling statutes, there is no “rational basis” for such a restriction (see Pierce v. Wellesley, 336 Mass. 517, 524 [1957]) and the by-law has no real or substantial relation to the statutory criteria. Jenckes v. Building Comm’r of Brookline, 341 Mass. 162, 166 (1960). Gem Properties, Inc. v. Board of Appeals of Milton, 341 Mass. 99, 105 (I960). Barney & Carey Co. v. Milton, 324 Mass. 440, 445 (1949). I would reach the same result, by applying the statutory criteria, if the by-law attempted to exclude, for example, only orthopedic clinics or only diabetes clinics. In my view, this statutory approach would, to say the least, be of greater value as precedent in treating future analogous cases than the constitutional approach unnecessarily adopted in the main opinion.