This bill for declaratory relief was reserved and reported by a single justice without decision. From the record (including stipulation and exhibits) the following circumstances appear.
The existing apportionment of seats in the State Senate (St. 1960, c. 432, § 2) no longer reflects, on the basis of the 1965 census, a distribution of seats proportional to the population of the respective senatorial districts. The population in 1965 of the largest Senate district (Middlesex-Worcester) was 211,265, which is 59.58% above the 1965 population of Massachusetts divided by 40. The arithmetical norm would be 132,382. The smallest district (3d Suffolk) contains 84,366 persons, a figure 36.28% below the 1965 norm.
1. The Supreme Court of the United States has recently held that a total spread, between the district with the highest *558population and that with the lowest population, of 5.96% of the average population of the districts was in violation of Federal constitutional principles. See Kirkpatrick v. Preisler, 394 U. S. 526, 528-529, 531, 533-536, reh. den. 395 U. S. 917. It is highly unlikely that, if tested in the Federal courts, any distribution of seats in a Statewide legislative body, having any avoidable disparity between the district with the highest population and that with the lowest, will be found to satisfy Federal constitutional requirements, at least in the absence of special circumstances not suggested on this record. Cf. Swann v. Adams, 385 U. S. 440, 442-445.
2. Relief against the continued use of a constitutionally invalid Senate apportionment is not barred by the ten day special statute of limitations found in St. 1960, c. 432, § 3. Even if c. 432 was valid when enacted, it has become unconstitutional by lapse of time. Vigeant v. Postal Tel. Cable Co. 260 Mass. 335, 342-344.
3. We are urged to take action ourselves to make a reapportionment of Senate seats. See Scott v. Germano, 381 U. S. 407, 409; Maryland Comm. for Fair Representation v. Tawes, 377 U. S. 656, 676; see also People ex rel. Engle v. Kerner, 33 Ill. 2d 11, 12-13; app. dism. 384 U. S. 30. Intervention in matters of reapportionment, even on matters of constitutionality, by any court is undesirable and to be avoided except as a last resort (and then only to satisfy constitutional mandates). Cf. Bowe v. Secretary of the Commonwealth, 320 Mass. 230, 243-247. We decline to take such action and do not pass upon its propriety in any event. The Legislature is still in session, and it remains possible that the Legislature itself will exercise that function, by enacting a Senate reapportionment plan. See Opinion of the Justices, 353 Mass. 790, 799.
4. A decree is to be entered in the county court declaring that the Senate apportionment provided by St. 1960, c. 432, § 2, has become unconstitutional and is invalid, and that it cannot be the basis of the 1970 election of senators.
So ordered.