Liacos, J.
In District Attorney for the Suffolk Dist. v. Watson, 381 Mass. 648 (1980), this court declared unconstitutional the capital punishment statute, c. 488 of the Acts of 1979. The court held that the penalty of death was impermissibly cruel under art. 26 of the Declaration of Rights of the Massachusetts Constitution.3 That article then provided, in its entirety: “No magistrate or court of law, shall demand excessive bail or sureties, impose excessive fines, or inflict cruel or unusual punishments.”
[152]*152On November 2, 1982, the voters approved a constitutional amendment which added a second and third sentence to art. 26: “No provision of the Constitution, however, shall be construed as prohibiting the imposition of the punishment of death. The general court may, for the purpose of protecting the general welfare of the citizens, authorize the imposition of the punishment of death by the courts of law having jurisdiction of crimes subject to the punishment of death.” Art. 116 of the Amendments to the Massachusetts Constitution. This amendment had been adopted by joint sessions of the General Court in the years 1980 and 1982.
On December 15, 1982, both Houses of the General Court enacted c. 554 of the Acts of 1982, providing for capital punishment in certain cases of murder in the first degree. The act was approved by the Governor on December 22, 1982, and took effect on January 1, 1983, to apply to offenses committed on or after the effective date. St. 1982, c. 554, § 8.
On the evening of February 26, 1983, State Trooper George L. Hanna was found on Route 20 in Auburn, injured by multiple gunshot wounds. He was taken to St. Vincent Hospital in Worcester, where he died later that evening as a result of the wounds. Complaints accusing the three defendants of the murder of Hanna issued shortly thereafter from the Worcester District Court. On April 4, 1983, the Commonwealth filed notice in the Worcester District Court that it would present evidence in accordance with the provisions of c. 554 of the Acts of 1982, and that the defendants “may suffer the punishment of death” pursuant to the procedures provided for by that chapter. In June, 1983, a Worcester County grand jury indicted each of the defendants for Hanna’s murder. The Commonwealth has indicated that these indictments will be tried separately. See Bruton v. United States, 391 U.S. 123 (1968).
On November 15, 1983, after hearings on a series of pretrial motions in the Superior Court, the Commonwealth moved, in each case, to report to the Appeals Court, pursuant to Mass. R. Crim. P. 34,378 Mass. 905 (1979), two questions of law:
“A. Whether G.L. c. 265, S. 2 and G.L. c. 279, Sections 4, 57-71, as most recently amended by St. 1982, [153]*153c. 554, S. 3-8, is in compliance with the Constitution of the United States.
“B. Whether G.L. c. 265, S. 2 and G.L. c. 279, Sections 4, 57-71, as most recently amended by St. 1982, c. 554, S. 3-8, is in compliance with the Constitution of the Commonwealth of Massachusetts.”
The Superior Court judge allowed the motion in each case over the defendants’ objections. From the evidence which he had received in connection with the pretrial motions and from the notice filed by the Commonwealth, the judge found that each defendant, if convicted, might be sentenced to death. He stated in each report that the question of the constitutionality of the death penalty statute was “so important... as to require the decision of the Appeals Court.” Mass. R. Crim. P. 34. After the reports were entered in the Appeals Court, the Commonwealth applied to this court for direct appellate review, and we allowed the application.4 We answer question B, “No,” on the ground that the statutory sections referred to in the question violate art. 12 of the Declaration of Rights of the Massachusetts Constitution by impermissibly burdening a defendant’s right against self-incrimination and right to trial by jury. In view of our answer to question B, we need not answer question A.5
[154]*154The propriety of deciding the constitutionality of the questioned provisions at this time. In our order allowing the application for direct appellate review, we noted that “[bjriefs may discuss the question whether this court should at this time decide any issue concerning the constitutionality of G. L. c. 265, § 2, and G. L. c. 279, §§ 4, 57-71, as amended by St. 1982, c. 554.” It is in this court’s discretion to postpone decision of issues reported before trial until appellate review after trial, “where such action seems more appropriate as a matter of judicial administration.” Commonwealth v. Benjamin, 358 Mass. 672, 673 n.1 (1971) (court, however, answered the questions reported). We recently discharged a report raising several constitutional questions because of our view that there was a preliminary question, not briefed, which should be decided before any constitutional issue was reached. Commonwealth v. Paasche, 391 Mass. 18, 21-22 (1984). There we stated that we do not decide constitutional questions unless they necessarily must be reached. Id. at 21.* ****6
The parties have briefed and argued the question whether we should discharge the reports without decision. Both the Commonwealth and the defendants urge us to decide the reported questions now, in so far as they concern the facial validity of the provisions at issue.7 Although the defendants [155]*155opposed the motions for report below because of the delay which would be occasioned in the commencement of their trials, their position now is that, since their trials already have been delayed by the reports, we should not render that delay useless by discharging the reported questions without decision.
“Interlocutory matters should be reported only where it appears that they present serious questions likely to be material in the ultimate decision, and that subsequent proceedings in the trial court will be substantially facilitated by so doing.” Commonwealth v. Henry’s Drywall Co., 362 Mass. 552, 557 (1972), quoting John Gilbert Jr. Co. v. C.M. Fauci Co., 309 Mass. 271, 273 (1941). Interlocutory reports, however, may be appropriate when the alternative is a prolonged, expensive, involved, or unduly burdensome trial. See Commonwealth v. Cavanaugh, 366 Mass. 277, 279 (1974).
We believe that the present case meets the criteria of appropriateness for an interlocutory report. The question of the constitutionality of the new death penalty legislation is one of substantial significance; indeed, it is one of public importance. See Commonwealth v. Haddad, 364 Mass. 795, 797 (1974). It is true that, if we declined to decide either of the reported questions at this stage of the proceedings, we might not have to decide them with respect to these three defendants. See District Attorney for the Suffolk Dist. v. Watson, 381 Mass. 648, 673 (1980) (Wilkins, J., concurring). However, if we waited to decide the constitutionality of the death penalty legislation until the question had to be answered, the consequence would be prolonged, expensive, involved, and unduly burdensome trials8 for both the Commonwealth and the defense, not [156]*156only in the case of each of these defendants, but also in every case arising in the meantime where the Commonwealth sought the death penalty, regardless of the eventual outcome of the case.* *******9 Whether or not the constitutionality of the death penalty legislation would have been a material question in the ultimate decision in the case of any particular defendant, proceedings in the trial court in all cases where the death penalty would have been sought will be substantially facilitated by our entertaining the interlocutory reports.
As the Commonwealth points out, by deciding as we do in the context of a pretrial report rather than after a sentence of death has been imposed, we spare a defendant the hardships which inevitably attend incarceration pending execution of a death sentence. See District Attorney for the Suffolk Dist. v. Watson, supra at 664-665. See also id. at 677, 678-679 n.5, 681,684-685 (Liacos, J., concurring). We also avoid the necessity of that defendant’s having to be resentenced or perhaps even retried.
Finally, it is to be remembered that in District Attorney for the Suffolk Dist. v. Watson, supra, we decided the constitutionality of this capital punishment statute’s predecessor in a proceeding begun by the district attorney by means of a complaint for a declaratory judgment. Four men who were awaiting trial on first degree murder indictments which might subject them to the death penalty had been permitted to intervene as defendants in that case. Id. at 649-650. Although we acknowledged [157]*157that declaratory relief will not be granted during the pendency of a criminal prosecution, absent very special circumstances, we concluded that the cases at bar were exceptional ones justifying declaratory relief “to prevent disruption of the orderly administration of criminal justice.” Id. at 659-660. If the issue of the facial validity of a death penalty statute properly could be decided in the context of a civil action for a declaratory judgment, we see no reason why it should not be decided in the context of a criminal prosecution by means of the procedure provided for by Mass. R. Crim. P. 34.
The propriety of deciding the constitutionality of the questioned provisions under the Massachusetts Constitution. The Commonwealth maintains that art. 116 of the Amendments to the Massachusetts Constitution provides immunity for any capital punishment statute from invalidation under any article of the Massachusetts Constitution. According to the Commonwealth, then, art. 116 prevents this court from scrutinizing St. 1982, c. 554, under any provision of the Massachusetts Constitution. We disagree.
Initially, we consider the aims of art. 116 in light of the text and structure of the provision. See Buckley v. Secretary of the Commonwealth, 371 Mass. 195, 199 (1976). As added by art. 116, the second sentence of art. 26 of the Declaration of Rights provides that no provision of the Massachusetts Constitution “shall be construed as prohibiting the imposition of the punishment of death.”
“An amendment to the Constitution is a solemn and important declaration of fundamental principles of government. It is characterized by terse statements of clear significance. Its words were employed in a plain meaning to express general ideas. It was written to be understood by the voters to whom it was submitted for approval. It is to be interpreted in the sense most obvious to the common intelligence. Its phrases are to be read and construed according to the familiar and approved usage of the language.” Yont v. Secretary of the Commonwealth, 275 Mass. 365, 366-367 (1931).
Webster’s New Int’l Dictionary 1978 (2d ed. 1959) defines “prohibit” as follows: “1. To forbid by authority or command; to [158]*158interdict; as, the law prohibits the sale of opiates or men from selling opiates . . . . 2. To stop or prevent (a person); to render impossible (an action); to hinder; debar.” The definition of “prohibit” given by Black’s Law Dictionary 1091 (5th ed. 1979) is “ [t]o forbid by law; to prevent; — not synonymous with ‘regulate. ’ ” We conclude that art. 26 now prevents this court from construing any provision of the Massachusetts Constitution, including art. 26 itself, as forbidding the imposition of the punishment of death. We do not, however, see anything in the new language of art. 26 which prevents us from invalidating a particular death penalty statute under the Massachusetts Constitution on a ground other than the imposition of the punishment of death is forbidden.10
[159]*159We do not consider that our invalidation of this statute is equivalent to prohibiting the imposition of the punishment of death. When, in Commonwealth v. Gagnon, 387 Mass. 567 (1982), we held that G. L. c. 94C, § 32 (a), was unconstitutionally vague and therefore was void, the Commonwealth lost the authority to execute the ten-year prison sentences which had been imposed on the defendants under that section. That result did not mean that we were construing either the United States Constitution or our own as prohibiting the imposition of ten-year sentences of imprisonment. Ten-year prison sentences are in themselves constitutional; the particular statutes which provide for them may be unconstitutional for a variety of reasons.11
[160]*160Our interpretation of the language of art. 116 is supported by its history, though that history is not controlling. See Buckley v. Secretary of the Commonwealth, supra at 200; Yont v. Secretary of the Commonwealth, supra at 369. As mentioned above, in 1980 a majority of this court ruled that the death penalty was impermissibly cruel under the then-existing version of art. 26. District Attorney for the Suffolk Dist. v. Watson, supra. In 1977 a majority of the Justices had given their opinion that the enactment of a death penalty bill pending before the Legislature — consisting of essentially the same substantive provisions as those later struck down in Watson — would violate art. 26. Opinions of the Justices, 372 Mass. 912 (1977). The Justices had stated that “art. 26 . . . forbids the imposition of a death penalty in this Commonwealth in the absence of a showing on the part of the Commonwealth that the availability of that penalty contributes more to the achievement of a legitimate State purpose — for example, the purpose of deterring criminal conduct — than the availability in like cases of the penalty of life imprisonment.” Id. at 917. In view of this opinion, the Justices had found it unnecessary to state an opinion on the question whether the enactment of the bill would violate arts. 1, 10, and 12. Id. at 921.
The first joint session of the General Court to adopt art. 116 did so on September 19, 1980, while Watson was pending before this court. The amendment was adopted in joint session by the next General Court on June 21, 1982. The sparse history of this amendment in the General Court sheds little light on the purpose for which it was adopted by either joint session. Nothing in that legislative history, however, indicates any notion that the amendment would shield all death penalty legislation from review under the Massachusetts Constitution.12 Nothing in the legislative history contradicts the natural inference that art. 116 was principally designed to overrule this [161]*161court’s interpretation of art. 26 as forbidding the death penalty and to forestall the possibility that any other provision of the Constitution would be interpreted thus. See Bowe v. Secretary of the Commonwealth, 320 Mass. 230, 241-243 (1946).
That inference is sustained by the summary of the proposed amendment which was circulated to the voters and was printed on the ballot in the manner required by the Massachusetts Constitution, art. 48, General Provisions III and IV of the Amendments, as amended by art. 74, § 4, and art. 108. That summary read: “The proposed constitutional amendment would allow the legislature to enact laws authorizing the state courts to impose the death penalty on the conviction of crimes to be specified by law. The proposed amendment would provide that no provision of the state constitution may in the future be construed as prohibiting the imposition of the punishment of death. A YES vote would change the state constitution to allow the State Legislature to authorize the death penalty for crimes. A NO vote would not change the present prohibition against the death penalty.” Nothing in the arguments for and against the amendment circulated to the voters concerned the total insulation of death penalty legislation from constitutional review.13
The words of an amendment “are to be construed in such way as to carry into effect what seems to be the reasonable purpose of the people in adopting them.” Raymer v. Tax Comm’r, 239 Mass. 410, 412 (1921). The construction of art. 116 which the Commonwealth urges us to adopt would mean that a statute establishing the death penalty for members of one particular race only or providing for the imposition of the death penalty without trial would be valid under the Massachusetts Constitution. In the absence of any indication to the contrary in the language and history of the amendment, we cannot accept the Commonwealth’s radical construction of art. [162]*162116 as carrying into effect the reasonable purpose of the people.14 See People v. Superior Court, 31 Cal. 3d 797, 806-809 (1982).15
[163]*163The unconstitutionality of the questioned provisions. The death penalty provisions enacted in St. 1982, c. 554, violate art. 12 of the Declaration of Rights of the Massachusetts Constitution. They impermissibly burden both the right against self-incrimination and the right to a jury trial guaranteed by that article.16 We base this conclusion on the fact that according to the terms of St. 1982, c. 554, the death penalty may be imposed, if at all, only after a trial by jury. Those who plead guilty in cases in which death would be a possible sentence after trial thereby avoid the risk of being put to death. The inevitable consequence is that defendants are discouraged from asserting their right not to plead guilty and their right to demand a trial by jury. For this reason, the answer to reported question B must be that G. L. c. 265, § 2, and G. L. c. 279, §§ 4, 57-[164]*16471, as most recently amended by St. 1982, c. 554, §§ 3-8, are not in compliance with the Constitution of the Commonwealth of Massachusetts.
Chapter 554 of the Acts of 1982 provides that the death penalty may be imposed in certain cases of murder in the first degree. The law of the Commonwealth allows a defendant to plead guilty to murder in the first degree. Commonwealth v. Balliro, 370 Mass. 585, 587 (1976). See G. L. c. 277, § 47;17 G. L. c. 263, § 6;18 Mass. R. Crim. P. 12 (a) (1), 378 Mass. 866 (1979).19 Of a predecessor20 of G. L. c. 263, § 6, the court said in 1866: “This explicit and unqualified enactment, which includes in its general language the crime of murder as well as all other offences, recognizes the rule which has always been the rule of the common law, that a party may be convicted on his own plea and confession in court, and that in such cases the intervention of a jury to determine his guilt is not necessary.” Green v. Commonwealth, 12 Allen 155, 167 (1866). In Commonwealth v. Balliro, supra, we ruled that the amend[165]*165ment of G. L. c. 265, § 2, by St. 1951, c. 203,21 to make a life sentence possible, in the jury’s discretion, when a defendant was found guilty of murder in the first degree, did not expressly or impliedly repeal G. L. c. 277, § 47, or G. L. c. 263, § 6.22 Likewise, neither the amendment of G. L. c. 265, § 2, by St. 1982, c. 554, § 3, nor any other section of St. 1982, c. 554, expressly or impliedly repealed those statutes or overruled Mass. R. Crim. P. 12 (a) (1) or the common law.23
If a defendant pleads guilty to murder in the first degree, he cannot be sentenced to death. As amended by St. 1982, c. 554, § 3, G. L. c. 265, § 2, provides in part: “Whoever is guilty of murder committed with deliberately premeditated malice aforethought or with extreme atrocity or cruelty, and who had attained the age of eighteen years at the time of the murder, may suffer the punishment of death pursuant to the procedures set forth in sections sixty-eight to seventy-one, inclusive, of chapter two hundred and seventy-nine. Any other person who is guilty of murder in the first degree shall be punished by imprisonment in the state prison for life.”24 Gen[166]*166eral Laws c. 279, § 68, inserted by St. 1982, c. 554, § 6, provides, in part: “In all cases in which a sentence of death may be imposed, the court shall submit to the jury special questions concerning the issue of murder in the first degree. If the jury determines beyond a reasonable doubt that the defendant is guilty of murder in the first degree, the jury shall specify whether the defendant is guilty of murder with deliberate premeditation, murder with extreme atrocity or cruelty, or murder in the commission or attempted commission of a crime punishable by imprisonment for life, or two or more of these. Upon a verdict of guilty of murder in the first degree with deliberate premeditation, or murder in the first degree with extreme atrocity or cruelty, a presentence hearing shall be conducted, unless the commonwealth stipulates that none of the aggravating circumstances as defined in paragraph (a) of section sixty-nine exists, before the jury before which the case was tried; provided, however, that if in the opinion of the judge presiding at the presentence hearing, it is impossible or impracticable for the trial jury to sit at the presentence hearing, a new jury shall be impanelled to sit at the presentence hearing. ”
Section 68 goes on to describe the presentence hearing and the process by which the jury is either to find, or not to find, that the death penalty shall be imposed, including certain findings to be made by the jury with respect to aggravating or mitigating circumstances. General Laws c. 279, § 70, inserted by St. 1982, c. 554, § 6, in turn provides: “Where, upon a trial by jury, a person is convicted of a crime which is punishable by death, a sentence of death shall not be imposed unless findings in accordance with section sixty-eight are made. Where such findings are made and the jury finds that the death penalty shall be imposed, the court shall sentence the defendant to death. Where such findings are not made or not unanimously made or where a sentence of death is not a unanimous finding by the jury, the court shall sentence the defendant to life imprisonment as provided in section two of chapter two hundred and sixty-five.”
Section 70 makes it clear that where the sentencing jury does not find unanimously for death, or does not make unani[167]*167mously the other findings required by § 68, the death penalty may not be imposed. In turn, § 68 makes clear the condition precedent to the presentence hearing on the basis of which the sentencing jury is to make these findings. That condition precedent is a verdict by the trial jury of guilty of murder in the first degree with deliberate premeditation or with extreme atrocity or cruelty. If there is no trial jury, there can be no such verdict and therefore no presentence hearing and no sentence of death.25
The Commonwealth argues that it was the intent of the Legislature that where a judge has approved a guilty plea to a charge of capital murder in the first degree,26 and thus there has been no trial or trial jury, a jury is to be empanelled to sit at a presentence hearing and to make a determination as to whether the death penalty shall be imposed. The Commonwealth relies in this argument on the provision in § 68 for the empanelment of “a new jury” to sit at the presentence hearing where, in the opinion of the judge, “it is impossible or impracticable for the trial jury to sit at the presentence hearing.” We find this argument strained. A statute is to be interpreted according to the plain and ordinary meaning of its words and their ordinary and approved usage. Rambert v. Commonwealth, 389 Mass. 771, 773 (1983). Commonwealth v. Galvin, 388 Mass. 326, 328 (1983). It is most doubtful that the Legislature would have referred to “the trial jury” or “a new jury” (emphasis supplied) in a provision which was meant to apply where there had been no trial jury. Also, if there had been no trial jury, the opinion of a judge would not be required as to the impos[168]*168sibility or.impracticability of the trial jury’s sitting at the pre-sentence hearing.
The Commonwealth overlooks two other aspects of § 68 which preclude the interpretation which it urges on us. First, whether the trial jury or a new jury sits at the presentence hearing, the condition precedent to the presentence hearing is “a verdict of guilty of murder in the first degree with deliberate premeditation, or . . . with extreme atrocity or cruelty” (emphasis supplied). Id. For there to have been such a verdict, there must have been a trial by jury.27 Finally, the Commonwealth overlooks the first sentence of § 68, which provides that “[i]n all cases in which a sentence of death may be imposed, the court shall submit to the jury special questions concerning the issue of murder in the first degree.” That sentence contemplates that in all cases where a sentence of death is possible, there will be a trial jury. In other words, where there is no trial jury, there can be no sentence of death.28
“Every rational presumption in favor of [a statute’s] validity must be indulged, and it will not be denounced as contrary to the Constitution unless its language is so clear and explicit as to render impossible any other reasonable construction.” Commonwealth v. O’Neil, 233 Mass. 535, 540-541 (1919). The language in St. 1982, c. 554, is so clear and explicit that we are unable to accept the Commonwealth’s interpretation of it as providing for the empanelment of a jury to determine whether the death penalty should be imposed on those who plead guilty.29 [169]*169We are precluded from accepting it not only by the language of c. 554 itself, but also by G. L. c. 277, § 47, which provides that one who pleads guilty to a capital crime shall be sentenced by the court.30
In Letters v. Commonwealth, 346 Mass. 403 (1963), the trial judge had threatened to impose harsher sentences if the defendants were found guilty at trial than if they pleaded guilty. This court expunged the defendants’ guilty pleas and reversed the judgments against them, stating that a defendant may not be punished for exercising his right to trial. Id. at 405. We said: “No matter how heinous the offense charged, how overwhelming the proof of guilt may appear, or how hopeless the defense, a defendant’s right to continue with his trial may not be violated. His constitutional right to require the Government to proceed to a conclusion of the trial [and] to establish guilt by independent evidence should not be exercised under the shadow of a penalty .... To impose upon a defendant such alternatives [a plea of guilty or the prospect of an unduly harsh sentence in the event of conviction] amounts to coercion as a matter of law.” Id. at 406, quoting United States v. Toteo, 214 F. Supp. 560, 567 (S.D.N.Y. 1963).
Recently, we have held that to allow a trial judge to consider, in sentencing, his belief that a defendant lied in his defense at trial impermissibly burdens a defendant’s right not to plead guilty and to testify. See Commonwealth v. Souza, 390 Mass. 813, 818 (1984); Commonwealth v. Coleman, 390 Mass. [170]*170797, 808 (1984). We so held as matter of State law, declining to follow United States v. Grayson, 438 U.S. 41, 54-55 (1978), in which the United States Supreme Court held that such conduct by a trial judge does not violate the Federal Constitution. See Souza, supra at 817-818; Coleman, supra at 807-808. See also id. at 804 & n.7.
We conclude that, if a judge may not penalize a defendant for asserting his right to trial or his right not to plead guilty by imposing a harsher sentence than he otherwise would have, neither may the Legislature authorize such penalization by such legislation as St. 1982, c. 554. This conclusion is supported by analogy to United States v. Jackson, 390 U.S. 570 (1968), in which the Supreme Court held unconstitutional the death penalty clause of the Federal Kidnaping Act, 18 U.S.C. § 1201 (a) (1964). Under that clause, in an interstate kidnapping case where the victim had not been liberated unharmed, the trial jury, and only the trial jury, could cause the defendant to be sentenced to death. A defendant who pleaded guilty or waived trial by jury31 could therefore avoid the risk of being put to death. The Supreme Court held that this scheme needlessly32 chilled the Fifth Amendment right not to plead guilty and the Sixth Amendment right to a jury trial. Whatever the power of Congress to impose a death penalty for violation of the Federal Kidnaping Act, it could not do so in this manner. Id. at581-583. See also State v. Frampton, 95 Wash. 2d 469, 478 (1981), where the court stated: “Where, pursuant to statutory procedure, the death penalty is imposed upon conviction following a plea of not guilty and a trial, but is not imposed when there [171]*171is a plea of guilty, that statute is unconstitutional.” A similar result was reached in Spillers v. State, 84 Nev. 23 (1968). In Spillers, the Nevada Supreme Court, relying on United States v. Jackson, 262 F. Supp. 716 (D. Conn. 1967), rev’d on other grounds, 390 U.S. 570 (1968), ruled that the penalty scheme of Nev. Rev. Stat. § 200.360(1) was unconstitutional in that it impermissibly burdened the defendant’s right to trial by jury, since a death penalty would be imposed only as a result of a jury verdict of guilty of rape. The Nevada court rested its decision on both the State Constitution and the Sixth Amendment to the Federal Constitution.33
The General Court may not authorize the imposition of the death penalty in a way which needlessly chills defendants’ art. 12 rights.34 Accordingly, the answer to reported question B is [172]*172that G. L. c. 265, § 2, and G. L. c. 279, §§ 4, 57-71, as most recently amended by St. 1982, c. 554, §§ 3-8, are not in compliance with the Constitution of the Commonwealth of Massachusetts.35