These consolidated appeals arise from a previous order of this Court1 in which we directed the District Court to determine, after a full hearing, numerous questions involving the application of the Maryland Defective Delinquents Act.2 Following an extensive series of hearings, and on consideration of the record of equally thorough proceedings in the state courts,3 the District Court dismissed the petitions.
The petitioners contend that, as applied, the Act is constitutionally deficient in the following respects:
1. The definition of defective delinquency is too vague to be susceptible to any objective medical or legal application, and in fact defective delinquency is not determined on an objective basis;
2. The examination procedures offend due process in that (a) a person suspected of being a defective delinquent is not given prior notice of the request *1155for examination, nor is he given an opportunity to contest the order referring him for examination; (b) he is required to submit to personal interviews with institutional psychiatrists, with a resulting risk of self-inerimination; and (c) he is not allowed to have an attorney present during the examination process;
3. The procedures for judicial determination of defective delinquency offend due process in that (a) hearsay evidence is admitted; (b) the state is not required to prove beyond a reasonable doubt, but only by a preponderance of the evidence, that the subject is a defective delinquent; (c) the indeterminate period of confinement, substituted for a previously imposed sentence of imprisonment for a term of years when a person is found to be a defective delinquent, violates the constitutional protection against double jeopardy;
4. The Act violates the prohibition against cruel and unusual punishment by including within its scope those persons whose conduct indicates a danger only to property rather than danger of violence to the person; and
5. Patuxent Institution lacks sufficient staff, facilities and finances to effectuate the purposes of the Act and, in consequence of these deficiencies, has failed to provide treatment as contemplated by the Act, thus depriving it of its character as a mental health institution and rendering it no more than a warehouse for obnoxious and antisocial elements of society.
The District Court considered each of these contentions in detail and found that the present application of the Act does not operate to deny any of the petitioners’ constitutional rights. We affirm on the District Court’s opinion. Sas v. State of Maryland, D.Md., 295 F.Supp. 389.
The Defective Delinquents Act is the outgrowth of Maryland’s dissatisfaction with the result of more conventional methods of dealing with habitual erim-inal offenders. In 1948 and 1949 two special commissions, one consisting of lawyers, judges, physicians, psychiatrists and psychologists appointed by the Governor, and the other made up of psychiatrists and psychologists appointed by the Board of Corrections, made studies of the medical and legal aspects of recidivism in an effort to suggest a more effective method of coping' with the problem. The result of the studies was a joint report recommending that a separate institution be established for “criminal mental and emotional defectives” with a diagnostic clinic to determine what persons were susceptible to specialized treatment in the institution. In 1951 the recommendations were adopted by the legislature. Patuxent Institution was established to house and care for defective delinquents, defined by the statute as including any
“individual who, by the demonstration of persistent aggravated antisocial or criminal behavior, evidences a propensity toward criminal activity, and who is found to have either such intellectual deficiency or emotional unbalance, or both, as to clearly demonstrate an actual danger to society so as to require such confinement and treatment, when appropriate, as may make it reasonably safe for society to terminate the confinement and treatment.” 4
The Act sets up a comprehensive scheme for referral, examination, commitment, treatment and release of persons suspected of being defective delinquents. A request for examination may be made only after the imposition of an active prison sentence upon a defendant’s conviction of one of several enumerated classes of criminal offenses.5 Examinations may be requested by the prosecutor, the Department of Correction, the trial judge on his own motion, or the de*1156fendant himself.6 An order referring- a defendant for examination is not reviewable. Once at Patuxent, the prisoner is examined by a physician, a psychiatrist and a psychologist, who are required to furnish a report to the committing court stating whether or not they believe him to be a defective delinquent. If the report is negative, he is returned to a penal institution to complete service of his sentence, with full credit for the time spent at Patuxent.7 If the examiners believe him to be a defective delinquent, he is afforded a full and prompt judicial hearing, at which he is entitled to the assistance of retained or appointed counsel8 and to receive a trial by jury.9 He is allowed full access to all records, reports and papers in the possession of the institution or the court, including the report made by the independent, private psychiatrist who, on the prisoner’s request, may be appointed to examine him at the expense of the state.10 If he is found to be a defective delinquent he is committed to Patuxent for an indeterminate period, with the right of judicial review of his classification after the expiration of the greater of two years or two-thirds of his original sentence, and thereafter at three year intervals. Appellate review of any court order subsequent to the original referral for examination is provided.11
In addition to periodic judicial determinations, the Act requires review of each inmate’s classification by the Institutional Board of Review not less than once each year.
The Board has the power to grant paroles or leaves of absence at any time, or to report to the committing court if it concludes that an inmate need no longer be classified as a defective delinquent.12 If the court concludes that his condition is so improved that confinement at Patuxent is no longer required, it máy order him returned to the Department of Correction to complete service of the original sentence with full credit for the time spent at Patuxent, order him released conditionally on parole or leave of absence, or order him released unconditionally, whether or not the original sentence would otherwise still be in effect.13
Critical to the appellants’ argument is the premise that, without regard to the terminology used, Patuxent is in fact a penal institution, and the proceedings for determination of defective delinquency are equivalent in practice to criminal prosecutions. Almost without out exception, their various contentions rest on this foundation.14 The District Court’s rejection of this basic contention, *1157which we affirm, of necessity defeats their arguments. As written by the legislature, construed by the courts, and applied by the staff, the Act selects a medically and legally recognizable class of persons for special treatment.15 Although criminal conduct is necessarily bound up in every case, the inquiry does not focus on particular criminal acts but on the menial and emotional condition of the person thought to be a member of the statutorily defined class. It is that, and no other factor, which ultimately determines his classification and treatment. In this context, the denomination of the proceedings as civil rather than criminal is not a semantic exercise but a factual description of what occurs. The procedural safeguards erected by the statute are adequate to meet present needs and to protect the petitioners’ constitutional rights.
In sum, the Act represents an enlightened and progressive experiment aimed at rehabilitating persons whose anti-social activities are occasioned, at least in part, by mental disorders. The present administration of the Act demonstrates a sincere and vigorous attempt to effectuate its policies. By the petitioners’ own account, the state has expended to date $28,000,000 for plant and facilities at Patuxent. Legislative appropriations for its operation have continuously increased, not only in absolute terms but also for each inmate and as compared with the appropriations for operating regular penal institutions. Currently the appropriations per inmate are three times the amount allocated to the Reformatory, four times that provided for the House of Correction, and five times the amount allotted for the Penitentiary. Improvements in and expansion of staff, therapeutic facilities, vocational and educational training, and out-patient services continue.16 There is reason to believe that the effort may prove successful. Based on the figures available from its brief operation, the recidivism rate from Patuxent, which deals with a population composed entirely of confirmed recidivists, is lower than the combined rate for all of the penal institutions in the United States.
We recognize that many problems remain and that there are many areas of possible improvement. For example, it might prove fruitful to permit the independent psychiatrist to participate in the proceedings at an earlier stage than is presently allowed; his participation in staff conferences may be beneficial to the staff and to the inmate he examines. But, in this comparatively new field of medical rehabilitation, experience is more likely than fiat to suggest constructive avenues for change.
*1158Mr. Chief Justice Burger has taken the lead in pleading for a reformation of our correctional system, which, in general, is woefully deficient in its rehabilitative function. Too many prisoners serve their allotted time and are released into society with the same predisposition to anti-social conduct as they had before their arrests. In all too many instances, imprisonment serves the converse of the rehabilitative purpose, converting good prospects for rehabilitation into hardened criminals. The result, of course, is a grave wrong for those convicts who could be helped by getting help. It is a grave wrong to society, which must suffer their continued depredations when released from prison until they are confined again.17
The interests of society and of the prison population demand the sort of innovative reappraisal of our correctional institutions, their practices and procedures, for which the Chief Justice has pled. At the very least, Patuxent is an encouraging example of one kind of approach to a solution of these difficult problems. Time is required to appraise its ultimate effectiveness, but there is firm foundation for hope that it will prove a material and positive step toward the rehabilitation of mental and emotional defectives, and the protection of society from those anti-social defectives who are beyond rehabilitation.
The approach of Maryland’s Defective Delinquent Act is essentially a medical approach, but the clear promise it has demonstrated would be withdrawn should it be held, as the petitioners contend, that the diagnostic and treatment processes must be converted into an adversary legal process in which the patient is entitled to all the constitutional protections available to a defendant in a criminal proceeding. It is difficult to imagine anything more stultifying to a psychiatrist, as dependent as he is upon the cooperation of his patient, than the presence of a lawyer objecting to the psychiatrist’s questions and advising his client not to answer this question and that. The injection of broad legal restraints into the diagnostic and treatment procedures that would deny Pa-tuxent’s substantial prospect for improvement over our earlier practices might well restrain most other experimentation looking toward conversion of our correctional institutions into effective rehabilitating agencies.18
The suggestion in the dissenting opinion that counsel be brought into the proceedings to a limited extent at an earlier time, like our similar suggestion with respect to the private psychiatrist, may have merit as one for future trial and experimentation. Its concededly tentative nature, in light of the uncertainties permeating this field of knowledge, however, hardly leads to the conclusion that it presently is an absolute requirement of the due process clause. The question before us is whether the procedures embodied in the statute meet the minimal requirements of the Constitution. In the appraisal of that question, settled notions of the essential elements of fairness play a great part, but the fact that we can conceive of tentative avenues for future trial experimentation to determine their impact upon the fairness of the procedures does not support a conclusion that our hesitant suggestions are already clad in the full regalia of due process.
The burden of persuasion is in the same category. We might all be happier had it been stated in terms of clear and convincing proof rather than in terms of a preponderance of the evidence. However meaningful the distinction may be to us as judges, however, it is greatly to be doubted that a jury’s *1159verdict would ever be influenced by the choice of one standard or the other. We all know that juries apply the preponderance standard quite flexibly, depending upon the nature of the case. In any event, in the present state of our knowledge, choice of the standard of proof should be left to the state. A legislative choice of the preponderance standard, the same standard governing civil commitments of mentally ill persons who have no history of criminality, ought not to be held in violation of due process requirements when we have no firm foundation for an evaluation of the practical effects of the choice.
Since the Act’s provision for judicial review of a defective delinquent’s initial commitment to Patuxent and his continued confinement there are adequate, we conclude that the Constitution does not require that the procedures under the Act be treated as if they were criminal proceedings subject to the self-defeating strictures which the Constitution appropriately throws around the shoulders of defendants facing criminal charges in adversary legal proceedings.
Affirmed.
. Sas v. State of Maryland, 4 Cir., 334 F.2d 506. The original petitioner is no longer a party to these proceedings. He was found to have responded favorably to treatment and was released from confinement. He did not join in this appeal.
. Annotated Code of Maryland, Article 31B.
. See Director of Patuxent Institution v. Daniels, 243 Md. 16, 221 A.2d 397.
. Annotated Code of Maryland, Article 31B § 5.
. Id., § 6(a).
. Id., § 6(b).
. Id., § 7(a).
. Id., § 8(a), (b).
. Id., § 8(c).
. Id., §§ 7(b), 8(b).
. Id., §§ 11, 11A. Although the time limitation on initial judicial reappraisal of an inmate’s status is of considerable length in the case of a long original sentence, the writ of habeas corpus is available without time limitations, and it is expressly preserved to inmates of Patuxent by § 10(c) of the Act. In addition, the Board of Review may seek judicial reappraisal of an inmate’s status at any time, pursuant to § 13 (f).
. Id., § 13(b), (d). Leaves of absence can be tailored by the Board of Review to meet individual needs. The leaves may range in length from a few days holiday leave, through longer periods designed to provide a basis for determining whether the inmate’s social interactions have significantly improved, to a full year’s leave to permit an inmate to live and work as a normal member of society, but subject to observation and supervision. In addition, a “live-in work-out” program has been devised to aid some inmates in coping with the transition between inmate status and full release. A “half-way house” has also been established to assist in the transition.
. Id., § 13(f).
. One contention which does not rest on this foundation is the claimed impropriety of including within the statutory class those persons who have demonstrated only a propensity for committing crimes carrying no danger of violence to the person. That question is not properly before us. Although the statute as construed permits this classification, the District Court found as a fact that it is not so applied *1157at the present time. None of these petitioners, nor any other person now confined at Patuxent, was classified as a defective delinquent solely on the basis of a propensity to commit only “property crimes.” The staff, as a matter of policy, does not recommend for classification as defective delinquents any such person. To the extent that a propensity to commit “property” crimes as well as a predisposition to violence or threats of violence may have been a factor in the classification of some of the petitioners, we can perceive no reason why the treatment provided at Patuxent should not be as beneficial in combatting that propensity as it is in dealing with more violent manifestations of mental disorder, nor why the state’s interest in treating it is any the less legitimate. The question raised by the petitioners need not be resolved unless and until the evaluation policies in effect at Patux-ent are changed to make operative the classification of which they complain.
. In Schreiber, Indeterminate Therapeutic Incarceration of Dangerous Criminals: Perspectives and Problems, 56 Va.L.R. 602, it is suggested that the statutory definition of “defective delinquent” should be made more specific. Although we recognize the risk of vagueness inherent in the terminology employed, an attempt to make precise legal definitions of medical concepts embodies a risk of over-definition. We do not think that the definition now used is so vague as to offend due process.
. Presently the staff at Patuxent includes ten psychiatrists, ten psychologists and fourteen social workers for approximately 350 inmates. The total psychiatric staff of all other correctional institutions in the entire United States is about fifty. See Schreiber, supra, note 35 at 607.
. See United States v. Chandler, 4 Cir., 393 F.2d 920, 927-929.
. We do not suggest that our disposition of these eases should be taken as a final and unalterable evaluation of all Constitutional questions which may arise out of the Act’s administration. We would not consider ourselves bound by today’s decision in a future case if later experience should show serious unfairness in the administration of the Act.