This criminal trespass case presents important issues concerning jury instructions on reasonable doubt, the supervisory function of this court over the trial courts of New Hampshire, and jury instructions on the elements of criminal trespass under RSA 635:2. Defendant raises four questions. This opinion, however, deals with only three; the fourth is fully addressed in the companion case of State v. Dorsey, 118 N.H. 844, 395 A.2d 855 (1978) (availability of the competing harms defense).
The issues to be decided are first, whether the trial court committed reversible error in instructing the jury that a reasonable doubt means "a strong and abiding conviction that still remains after a careful consideration of all of the evidence"; second, whether the court erred in instructing the jury on the elements of criminal trespass; and third, whether the court abused its discretion in sentencing the defendant to six months, two months suspended, in the house of correction. We hold that no error was committed.
The pertinent facts are these. The defendant was arrested along with about 1,400 other protesters at the May 1977 occupation of the Seabrook Nuclear Power Plant site. He was charged with the crime of criminal trespass, RSA 635:2, and was convicted in the District Court for the Town of Hampton. Defendant was fined $100, sentenced to fifteen days in the house of correction and appealed his conviction to the superior court. A jury trial resulted in a verdict of guilty, and he excepted to various rulings and instructions, and also to the increase of his sentence. All issues of law were reserved and transferred by Mullavey, J.
I. Jury Instruction on Reasonable Doubt
The defendant challenges the constitutionality of the jury instruction on the reasonable doubt standard given in his trial. The actual charge given follows:
Defendant contends that the recent First Circuit opinion of Dunn v. Perrin, 570 F.2d 21 (1st Cir. 1978), cert. denied, 98 S.Ct. 3102 (1978), mandates a finding of reversible error based upon the trial court's use of the phrase "a strong and abiding conviction." We disagree with the defendant's position for two reasons: first, we find the present jury instruction distinguishable from that held invalid in
In the cases of State v. Black, 116 N.H. 836, 368 A.2d 1177 (1976), and State v. Belkner, 117 N.H. 462, 374 A.2d 938 (1977), this court refused to find reversible error in jury instructions containing, among others, the questioned definition of reasonable doubt. In both cases, this court made it clear that it was on the basis of the entire charge that we found no reversible error. State v. Belkner, 117 N.H. at 471, 374 A.2d at 944; State v. Black, 116 N.H. at 838, 368 A.2d at 1179. Both cases, moreover, quoted the Supreme Court of the United States to the effect that "a single instruction to a jury may not be judged in artificial isolation, but must be viewed in the context of the overall charge." Cupp v. Naughten, 414 U.S. 141, 146-47 (1973); accord, United States v. Park, 421 U.S. 658, 674 (1974). In Dunn v. Perrin, 570 F.2d 21 (1st Cir. 1978), cert. denied, 98 S.Ct. 3102 (1978), the defendants from the two New Hampshire cases sought relief by petitions for habeas corpus in the federal district court, but the district court agreed with this court and denied the requested relief. On appeal, the Court of Appeals for the First Circuit reversed, holding that the instruction given contained three erroneous definitions of the reasonable doubt standard.
The court of appeals was quite specific as to its perceived need for a reversal:
Dunn v. Perrin, 570 F.2d at 25 (citations omitted).
The jury instruction held invalid in Dunn v. Perrin defined reasonable doubt (1) as "doubt as for the existence of which a reasonable person can give or suggest a good and sufficient reason," (2) as "a strong and abiding conviction as still remains after careful consideration of all the facts and arguments," and (3) as a standard requiring proof to a moral certainty. Such instructions have been used in this State for decades without challenge. The jury instruction in the present case, however, included only the second of those three definitions.
It is the opinion of this court that the Dunn case must be limited to its facts. The First Circuit twice emphasized that its decision was based upon the cumulative effect of the three reasonable doubt
 We now hold that considering the charge as a whole the instruction given in the present case is not such error as to require a reversal. Even assuming that the defendant is correct in his assertion that the Dunn case is controlling on this court, we hold that, on its facts, it is not controlling in this case.
This court further disagrees with the contention of the defendant and the First Circuit that the language "a strong and abiding conviction as still remains after careful consideration of all the facts" works a reversal of the burden of proof. The defendant argues strenuously that this definition, "[i]nstead of requiring the government to prove guilt, . . . called upon [the defendant] to establish doubt in the jurors' minds." Dunn v. Perrin, 570 F.2d at 24. We are unable to see how this is so. The definition given by the trial judge in the present case simply contrasts a reasonable doubt with one that is slight or frivolous. The judge stated: "[N]or do we require that the State remove all slight or frivolous doubt from your minds, but . . . all reasonable doubt must be removed by the evidence which you have heard presented by the State." (Emphasis added.) The judge then attempted to define the elusive standard of reasonable doubt. Taken in context, we cannot agree that the burden of proof was shifted to the defendant. Rather than placing the burden on the defendant to create the doubt, the instruction required the State to remove it.
 The charge plainly stated that "[t]he defendant . . . [had] no burden of proving anything." The charge also made it clear that the burden was on the State to prove each element of the offense beyond a reasonable doubt. These repeated admonitions to the jury undermine any argument that the "strong and abiding conviction" language shifted the burden of proof to the defendant. Taken in its entirety the instruction "conveyed the correct concept of reasonable doubt." State v. Belkner, 117 N.H. 462, 471, 374 A.2d 938, 944 (1977); State v. Black, 116 N.H. 836, 368 A.2d 1177 (1976). See also Cupp v. Naughten, 414 U.S. 141, 146-47 (1973). In addition, even assuming that it was error to instruct the jury in the manner selected, "any possible prejudicial effect of the phrase was harmlessly lost in the totality of the instructions." State v. Black, 116 N.H. at
In sum, we are unable to agree with the defendant that this is a case controlled by Dunn v. Perrin, 570 F.2d 21 (1st. Cir. 1978). This cannot be said to be an instance where the effect of the instruction "was to obfuscate one of the `essentials of due process and fair treatment.'" Id. at 25, quoting In re Winship, 397 U.S. 358, 359 (1969). We are also unable to agree with either the defendant or the First Circuit that the phrase "strong and abiding conviction," when taken in context, operates to shift the burden of proof to the defense. Were it to do so, we would have no recourse but to reverse. RSA 625:10; In re Winship, 397 U.S. 358, 364 (1969).
 Defendant's contention that the court further erred in instructing the jury that a reasonable doubt exists "where our belief in a fact is so uncertain that we would hesitate to act upon the strength of it to undertake something of importance and seriousness equal to this case" is foreclosed by Dunn v. Perrin, 570 F.2d at 24-25. As noted in that case, the above-quoted instruction has received widespread approval. See Holland v. United States, 348 U.S. 121, 140 (1954); United States v. Robinson, 546 F.2d 309, 313 (9th Cir. 1976); United States v. Dixon, 507 F.2d 683, 684 (8th Cir. 1974). We find these authorities persuasive, and hold that no error was committed.
 This court is cognizant of the long history of challenges to jury instructions concerning the reasonable doubt standard. See generally F. Wharton, Criminal Evidence § 12 (13th ed. 1972) and cases cited therein. Mindful of the uncertainties spawned by continued litigation, and aware of the importance of a smooth functioning criminal justice system, we are now prepared to exercise our supervisory jurisdiction over the trial courts of New Hampshire, N.H. CONST. pt. II, art. 73-A and RSA 490:4, and to instruct those courts regarding jury instructions relative to reasonable doubt.
To avoid needless litigation, the following model charge is suggested:
We caution our trial judges to avoid attempts at further defining reasonable doubt. In many instances, further definition leads only to further complication and needless litigation. See Orrill v. State, 509 P.2d 930 (Okla. Crim. App. 1973); Cosco v. State, 521 P.2d 1345 (Wyo. 1974).
II. Jury Charge on Elements of Offense
The defendant argues that the trial court did not make clear to the jury that defendant must be found to have known that he was not "licensed or privileged" to remain on the property before a guilty verdict could be returned. We reject this argument.
RSA 635:2 provides in part: "A person is guilty of criminal trespass if, knowing that he is not licensed or privileged to do so, he enters or remains in any place...." An essential element of the crime is that the defendant know that he was not licensed or privileged to enter or remain on the premises.
In the case before us the court charged the jury as follows:
Defendant and the Civil Liberties Union maintain that the sentence of six months in the house of correction, two months suspended, for a first-time offender is unconstitutionally disproportionate and constitutes cruel and unusual punishment. They argue that a major disparity exists between this sentence and those received by others for the same offense, that the court failed to consider defendant's background and rehabilitative prospects, and that the court punished defendant more harshly because of his adherence to civil disobedience, thus denying him equal protection of the law, due process, and freedom of speech in violation of both the Constitutions of the United States and this State. We reject these arguments.
The legislative authorization for a maximum sentence in a criminal trespass case is one-year imprisonment and a $1,000 fine. RSA 651:2. Defendant's sentence is half this maximum, and the time he is required to serve after suspension is only one-third of the maximum authorized with a probable reduction of one-third of the four months. RSA 651:18. The State admits that the sentence in this and the related cases arising out of the Seabrook demonstrations may be higher than those usually imposed in ordinary criminal trespass cases and are substantially higher than those imposed by the district court from which appeal was taken.
 The real purpose of all sentencing is to reduce crime. This theoretically can be done by rehabilitating the individual defendant so he will not offend again. Another way is to punish the individual defendant in the hope that he will be deterred from repeating his crime. Moreover, by punishing the individual defendant, others may be deterred from committing crimes. Whichever sentence is thought to be likely to reduce the most crime is the proper sentence to impose.
 Contrary to defendant's assertion, the emphasis on deterrence in this case is not inconsistent with N.H. Const., pt. I, art. 18, which states in part that "the true design of all punishments [is] to reform, not to exterminate mankind." It should be noted that this constitutional language sanctions "punishment" as a method of reforming the criminal. See State v. Farrow, 118 N.H. 296, 386 A.2d 808 (1978). This same language also recognizes deterrence as a valid purpose of sentencing; the implication is that reform will result from the deterrent effect of punishment. General deterrence is also recognized in other language in the article when it states that if the same "severity is exerted against all offenses, the people are led . . . to commit the most flagrant with as little compunction as they do the lightest offenses." Id. Rehabilitation, which in the modern sense of the word includes counseling and training, is not a constitutional requirement.
 The defendant in this case is an educated, highly motivated individual with no prior record and with no apparent criminal tendencies apart from the practice of civil disobedience to accomplish what he considers to be an important goal. He is not in need of rehabilitation in the modern sense of the word. The State, however, does need to deter repetition of this offense both by the defendant and others. Both individual and general deterrence were important considerations for the imposition of sentence in this and related cases. To accomplish these purposes, the sentence needed to be more severe than in ordinary criminal trespass cases. In deciding on the
 Although we recognize that, as defendant argues, the constitutional prohibitions against cruel and unusual punishments might be violated by sentences which are grossly disproportionate to the crime, see Robinson v. California, 370 U.S. 660, 667 (1962); Coker v. Georgia, 433 U.S. 584, 591-92 (1977), and that sentences might be so disproportionate as to constitute an abuse of discretion, see Benton v. Dover District Court, 111 N.H. 64, 274 A.2d 876 (1971), no such error exists in this case.
[11-13] Nor was the sentence in this case a denial of due process, equal protection of the law, or freedom of speech under either constitution. There is no indication here that the trial court failed to consider the individual defendant in imposing sentence or that the court rested the sentence on impermissible grounds. General deterrence is a permissible consideration. United States v. Wardlaw, 576 F.2d 932 (1st Cir. 1978). The sentences were not imposed to deter freedom of expression but to deter illegal actions. There has been no restraint on the lawful exercise of rights protected by the first amendment. We hold that, on the record before us, there was no illegality in the sentence and no abuse of discretion.
BOIS, J., did not sit; the others concurred.