These cases are before us on an interlocutory transfer without ruling from the Superior Court (Cann, J.). The sole *307question before us that was briefed and argued is whether RSA 651:ll-a, I (Supp. 1983), if applied to this defendant, would be an illegal retrospective or ex post facto law. We rule that RSA 651:ll-a, I (Supp. 1983), if applied to this defendant and those similarly situated, would be a retrospective law violative of the New Hampshire Constitution, part I, article 23.
The operative facts are summarized from the agreed statement of facts in the interlocutory transfer. On June 4, 1980, the defendant was indicted on a charge of second-degree assault (RSA 631:2 (Supp. 1983)) alleged to have occurred on March 22, 1980. On October 22, 1980, the defendant entered a plea of not guilty by reason of insanity, and the plea was accepted by the Superior Court (Contas, J.). The defendant was subsequently committed to the New Hampshire State Hospital “for life until or unless earlier discharged, released, or transferred by due course of law.” RSA 651:9 (Supp. 1983).
When the defendant entered his plea of not guilty by reason of insanity, RSA 651:ll-a provided:
“Orders of committal or transfers to the state hospital made pursuant to this chapter shall be valid for 2 years. For the order to be renewed, another judicial hearing must be held. At the renewal hearing, when the court is satisfied by a preponderance of the evidence that the hospital patient suffers from mental disease and that it would be dangerous for him to go at large, the court shall renew the order of committal or transfer.”
Part of this statute had been found unconstitutional because it permitted recommittal based on a mere preponderance of the evidence, rather than based on proof beyond a reasonable doubt. State v. Gregoire, 118 N.H. 140, 384 A.2d 132 (1978).
Effective May 22, 1982, the legislature amended RSA 651:ll-a to extend the validity of orders of committal from two to five years. After seeking our advice, the legislature revised the standard for recommitments to that of proof beyond a reasonable doubt. See Opinion of the Justices, 122 N.H. 199, 202, 442 A.2d 594, 596 (1982); RSA 651:11-a, I (Supp. 1983).
In August 1982, the State petitioned for the recommittal of the defendant to the New Hampshire Hospital. The defendant filed a motion in limine in which he contended that any recommittal order could not exceed two years because, if applied to him, RSA 651:ll-a (Supp. 1983) would be an unconstitutional retrospective law in violation of the New Hampshire Constitution, part I, article 23, and an unconstitutional ex post facto law violative of the United States Con*308stitution, article I, section 10, clause 1. Why the motion was denominated in limine on these facts is unknown.
On November 18, 1982, the Superior Court (Cann, J.), after the so-called “Gibbs” hearing, found beyond a reasonable doubt that the defendant was “presently suffering from a mental disorder and that it [would] be dangerous for him to go at large.” The court ordered the defendant recommitted to the New Hampshire Hospital, did not rule on the defendant’s motion, and transferred to this court the questions raised in the motion.
In a separate appeal, that was consolidated with this case, the defendant challenged his recommittal based on the sufficiency of evidence and alleged evidentiary errors. These issues were not briefed or argued on appeal and therefore we will not address them. See D. W. Clark Road Equipment, Inc. v. Murray Walter, Inc., 124 N.H. 281, 469 A.2d 1326 (1983).
The New Hampshire Constitution forbids retrospective or ex post facto laws. “Retrospective laws are highly injurious, oppressive, and unjust. No such laws, therefore, should be made, either for the decision of civil causes, or the punishment of offenses.” N.H. Const, pt. I, art. 23. The policy underlying “this prohibition is to prevent the legislature from interfering with the expectations of persons as to the legal significance of their actions taken prior to the enactment of a law.” State v. Vashaw, 113 N.H. 636, 637-38, 312 A.2d 692, 693 (1973). This court has reiterated on numerous occasions that this provision “prohibits the enactment of any law which ‘creates a new obligation, imposes a new duty, or attaches a new disability in respect to transactions . . . already past....’” State v. Vashaw, supra at 637, 312 A.2d at 693 (quoting Pepin v. Beaulieu, 102 N.H. 84, 89, 151 A.2d 230, 235 (1959) (quoting Woart v. Winnick, 3 N.H. 473, 479 (1826))).
In our most recent criminal case dealing with the ex post facto prohibition, we held that the defendant was not significantly deprived of a “meaningful opportunity to seek a suspension of his sentence” by the operation of a new statute that eliminated the unlimited right to seek a sentence suspension. State v. Theodosopoulos, 123 N.H. 287, 291, 461 A.2d 100, 103 (1983). In other words, the new statute did not create a “new disability.” State v. Vashaw supra.
We have stated that “ex post facto or retrospective laws are generally violative of both the U.S. Const, art. I, § 10 and the N.H. Const, pt. I, art. 23.” State v. Lambert, 119 N.H. 881, 884, 409 A.2d 794, 796 (1979). This position is equally true today. Under the Federal Constitution, the ex post facto clause prohibits laws which *309are “retrospective,” and “disadvantage the offender.” Weaver v. Graham, 450 U.S. 24, 29 (1981).
To the extent that State v. Theodosopoulos supra required a “substantial disadvantage,” it falls short of the federal minimum required by Weaver supra. While the result in Theodosopoulos would be the same, we reaffirm that the test is merely “disadvantage.” See State v. Ball, 124 N.H. 226, 231, 471 A.2d 347, 350 (1983) (“the role of the Federal Constitution is to provide the minimum level of national protection”).
We apply the standards applicable in criminal matters to this case because we have repeatedly said that recommitments pursuant to RSA 651:ll-a (Supp. 1983) are criminal proceedings. See Opinion of the Justices, 122 N.H. at 203, 42 A.2d at 595 (1982) (“reasonable doubt standard of proof was constitutionally required in criminal recommitment hearings.”); State v. Gregoire, 118 N.H. 140, 142, 384 A.2d 132, 133 (1978) (“we held that in a criminal recommitment hearing”); see also Proctor v. Butler, 117 N.H. 927, 932, 380 A.2d 673, 676 (1977) (quoting In re Miller, 98 N.H. 107, 108-09, 95 A.2d 116, 117 (1953)) (“Due process of law is not to be circumvented by use of the term civil as applied to proceedings which may have the same effect as criminal proceedings”); see generally State v. Paradis, 123 N.H. 68, 455 A.2d 1070 (1983).
In Novosel v. Helgemoe, 118 N.H. 115, 119, 384 A.2d 124, 126 (1978), we recognized that “[t]he legislature clearly has in mind a separate class when criminal commitment is concerned.” This legislative intent is further evinced by examining the statutory scheme applicable to insanity acquittees. The discharge, absences, parole, and hearings involving insanity acquittees are governed by RSA 135:28 to :30-a, while RSA 135-B:26 to :41 governs those civilly committed.
Prior to the discharge or granting of off-grounds privileges “to any person committed to the hospital by criminal proceedings, the superintendent shall give notice ... to the superior court. . . and to the office of the prosecutor . . . .” RSA 135:28-a. The effect of this statute is that the court actually decides when the insanity acquittee may be released. See 2 R. McNamara, New Hampshire Practice, Criminal Practice and Procedure § 906 (1980). In contrast, RSA 135-B:39 (Supp. 1983) provides that those civilly committed may be discharged from treatment by the administrator of the hospital with the consent of a psychiatrist. Off-grounds privileges are not regulated at all by statute for civilly committed patients, but they are for , the criminally insane.
*310The continued jurisdiction of the superior court over the insanity acquittee is illustrated by RSA 135:29: “On due cause shown, [the court may] parole any person committed to the hospital by criminal proceedings . . . .” There is, of course, no provision for the parole of those civilly committed because they are not criminally committed. See RSA 135-B:26 to :41.
In RSA 135:30-a, the conduct of hearings and the rights of insanity acquittees at those hearings are delineated, while the analogous provisions for persons civilly committed are set forth in RSA 135-B:26 to :41. At the present time, the forensic unit in which insanity acquittees are housed is a 41-bed facility located on the grounds of the New Hampshire Hospital. However, there are plans to construct a new forensic unit with 60 beds on the grounds of the State prison. The groundbreaking for the new unit is scheduled to take place in 1984, and occupancy is scheduled for the fall of 1985.
The dissent’s reliance on In re Moulton, 96 N.H. 370, 77 A.2d 26 (1950) is misplaced. In Moulton, we held that proceedings involving dangerous sexual offenders were constitutional because they were civil as “section 1 specifically calls for ‘a civil commitment.’” Id. at 373, 77 A.2d at 28. While proceedings pursuant to RSA chapter 173-A were not a part of the Criminal Code, that chapter has since been repealed and is thus irrelevant to our discussion. Laws 1983, 206:1.
With this background in mind, we now turn to the defendant’s contention that RSA 651:ll-a, I (Supp. 1983), as applied to him, is violative of the retrospective provision of the New Hampshire Constitution because it disadvantages him. Because we rule that RSA 651:11-a, I (Supp. 1983) violates the New Hampshire Constitution, part I, article 23, we do not reach the federal constitutional question. See State v. Ball, 124 N.H. 226, 231, 471 A.2d 347, 350 (1983).
The defendant was indicted in 1980, for a crime alleged to have occurred earlier that year, and in 1980 he pled not guilty by reason of insanity, and was committed to the New Hampshire Hospital. RSA 651:ll-a, I (Supp. 1983), extending the validity of the commitment order from two to five years, was enacted in 1982. It is indisputable that, when applied to this defendant, RSA 651:ll-a, I (Supp. 1983) is a retrospective law.
The sole question presented for our determination, therefore, is whether the actual operation of RSA 651:ll-a, I (Supp. 1983) disadvantages the defendant. See State v. Theodosopoulos, supra at 290, 461 A.2d at 102. The State contends that RSA 651:ll-a, I (Supp. 1983) does not disadvantage the defendant because he can petition the court to review his commitment status at any time, see RSA *311135:28, :29, or :30-a, and because the burden of proof is merely procedural, thus not affecting a substantive right. We cannot agree with the State’s position, for two reasons: RSA 651:ll-a, I (Supp. 1983) implicitly places the burden of petitioning the court for a hearing and the burden of proof on the defendant, should he request a hearing sooner than the five years provided for by the statute. These distinct additional burdens both disadvantage the defendant.
When the State petitions to commit or recommit a defendant under RSA 651:ll-a, I (Supp. 1983), the State must initiate the proceedings, and the defendant is guaranteed legal representation in accordance with New Hampshire Superior Court Administrative Rule 11-7. When a defendant seeks to have his commitment status reviewed under RSA 135:28, :29, or :30-a, he must initiate the proceedings and legal representation is not provided. See Super. Ct. Admin. Rules 11-1 to 11-5; see also 2 R. McNamara, New Hampshire Practice, Criminal Practice and Procedure § 906 (1980). To fail to recognize that this distinction places the defendant at a disadvantage would be to overlook the practical realities of the institutional life of a mental patient. See Note, Substantive Due Process Limits On The Duration of Civil Commitment For the Treatment of Mental Illness, 16 Harv. C.R.-C.L. L. Rev. 205, 219-23 (1981) (hereinafter Harvard Note).
The Connecticut Supreme Court recently addressed this issue as applied to civilly committed patients and found that the procedure was inadequate because it placed the burden of initiating review on the patient. Fasulo v. Arafeh, 173 Conn. 473, 480, 378 A.2d 553, 556 (1977). The court stated that
“to require a patient to initiate judicial review of his confinement and to bear the burden of proving the nonexistence of the necessity for that confinement ignores the practical considerations discussed above which are inherent in the mental patient’s situation. Briefly, these include the difficulties of overcoming an isolated environment to initiate and coordinate a challenge to one’s confinement. For instance, we cannot assume that friends and allies will always be available to secure counsel and marshal evidence on the patient’s behalf.”
Id. at 481, 378 A.2d at 557. See Harvard Note, supra at 221. The State of Connecticut attempted to justify the procedure of requiring the patient to initiate judicial review on the ground that it would “avoid unnecessary judicial proceedings.” Id. at 482, 378 A.2d at 557. The court responded to this argument stating:
*312“We doubt whether this rationale is adequate since it ignores the practical difficulties of requiring a mental patient to overcome the effects of his confinement, his closed environment, his possible incompetence and the debilitating effects of drugs or other treatment on his ability to make a decision which may amount to the waiver of his constitutional right to a review of his status.”
Id. See generally Harvard Note supra.
This reasoning of the Connecticut Supreme Court appears well founded to us. We rule, therefore, that a disadvantage is created by a procedure which shifts the burden of initiating judicial review of commitment status, for those who were committed prior to the enactment of RSA 651:ll-a (Supp. 1983), and who desire review of their commitment status more frequently than the five-year review provided for now. Id.
The State also argues that RSA 651:ll-a, I (Supp. 1983) is not an unconstitutional retrospective law because it is merely a procedural change. At the five-year recommitment hearing, RSA 651:ll-a, I (Supp. 1983) places the burden of proof beyond a reasonable doubt on the State. When a defendant desires review of his commitment status prior to the expiration of the five- or two-year period, he must initiate the review and he bears the burden of proof by a preponderance of the evidence. See State v. Hesse, 117 N.H. 329, 331, 373 A.2d 345, 346 (1977); see also 2 R. McNamara, New Hampshire Practice, Criminal Practice and Procedure § 906 (1980). The State contends that this shifting of the burden of proof does not disadvantage the defendant. We do not agree.
This court has repeatedly recognized the significance of the different burdens of proof and their effect on the party on whom they are cast. This is especially true in proceedings involving the commitment of mentally ill persons, “[bjecause the consequences of erroneous confinement are so serious, this court adopted a ‘beyond a reasonable doubt’ standard.” Opinion of the Justices, 122 N.H. 199, 202, 442 A.2d 594, 595 (1982). The rationale underlying our adoption of this stringent standard in part was “the speculative nature of psychiatric diagnosis and prognosis and the conflicting opinions of psychiatric experts.” Id.
In State v. Gregoire, 118 N.H. 140, 384 A.2d 132 (1978), we stated that “[w]e required the higher standard of proof in both Gibbs v. Helgemoe and Proctor v. Butler not only because of the vital interest in liberty, but also because of the established fact that psychiatric opinions are far from infallible.” Id. at 143, 384 A.2d at 133. “Only *313by raising a high standard, i.e., one that excludes confinement in cases of reasonable doubt, can the risk of erroneous recommitment be reduced and the liberty guaranteed by N.H. Const, pt. I, art. 15, be protected and assured.” Id. at 143-44, 384 A.2d at 134. Finally, in Gibbs v. Helgemoe, 116 N.H. 825, 367 A.2d 1041 (1976), we said that the “[e]ssential elements in a commitment hearing are the nature of the burden of proof and on whom it is imposed.” Id. at 828, 367 A.2d at 1043.
Today we are asked by the State to rule that RSA 651:ll-a, I (Supp. 1983) as applied to this defendant is not a retrospective law. To do this, we would have to rule that shifting the burden of proof from the State to the defendant, when the defendant seeks a more frequent review of his commitment status than now provided for by RSA 651:ll-a, I (Supp. 1983), does not disadvantage the defendant. An opinion consistent with this position would, of necessity, significantly downgrade the importance and impact of the burden of proof in hearings for the commitment and recommitment of the mentally ill which we have held in our prior decisions to be essential. In order to remain consistent with Gibbs v. Helgemoe supra, and its progeny, and to reaffirm our belief in the importance of the burden of proof, we decline to rule as the State requests.
Remanded.
Souter, J., and Brock, J., dissented in part.