delivered the opinion of the Court.
The Court granted certiorari in this case to determine whether involuntarily committed mental patients have a constitutional right to refuse treatment with antipsychotic drugs.
I
This litigation began on April 27, 1975, when respondent Rubie Rogers and six other persons filed suit against various officials and staff of the May and Austin Units of the Boston State Hospital. The plaintiffs all were present or former mental patients at the institution. During their period of institutionalization all had been forced to accept unwanted treatment with antipsychotic drugs.1 Alleging that forcible *294administration of these drugs violated rights protected by the Constitution of the United States, the plaintiffs — respondents here — sought compensatory and punitive damages and injunctive relief.2
The District Court certified the case as a class action. See Rogers v. Okin, 478 F. Supp. 1342, 1352, n. 1 (Mass. 1979). Although denying relief in damages, the court held that mental patients enjoy constitutionally protected liberty and privacy interests in deciding for themselves whether to submit to drug therapy.3 The District Court found that an involuntary “commitment” provides no basis for an inference of legal “incompetency” to make this decision under Massachusetts law. Id., at 1361-1362.4 Until a judicial finding of *295incompetency has been made, the court concluded, the wishes of the patients generally must be respected. Id., at 1365-1368. Even when a state court has rendered a determination of incompetency, the District Court found that the patient’s right to make treatment decisions is not forfeited, but must be exercised on his behalf by a court-appointed guardian. Id., at 1364. Without consent either by the patient or his guardian, the court held, the patient’s liberty interests may be overridden only in an emergency.5
The Court of Appeals for the First Circuit affirmed in part and reversed in part. Rogers v. Okin, 634 F. 2d 650 (1980). It agreed that mental patients have a constitutionally protected interest in deciding for themselves whether to undergo treatment with antipsychotic drugs. Id., at 653.6 It *296also accepted the trial court’s conclusion that Massachusetts law recognizes involuntarily committed persons as presumptively competent to assert this interest on their own behalf. See id., at 657-659. The Court of Appeals reached different conclusions, however, as to the circumstances under which state interests might override the liberty interests of the patient.
The Court of Appeals found that the State has two interests that must be weighed against the liberty interests asserted by the patient: a police power interest in maintaining order within the institution and in preventing violence, see id., at 655, and a parens patriae interest in alleviating the sufferings of mental illness and in providing effective treatment, see id., at 657. The court held that the State, under its police powers, may administer medication forcibly only upon a determination that “the need to prevent violence in a particular situation outweighs the possibility of harm to the medicated individual” and that “reasonable alternatives to the administration of antipsychotics [have been] ruled out.” Id., at 656. Criticizing the District Court for imposing what it regarded as a more rigid standard, the Court of Appeals held that a hospital’s professional staff must have substantial discretion in deciding when an impending emergency requires involuntary medication.7 The Court of Appeals reserved to the District Court, on remand, the task of developing mechanisms to ensure that staff decisions under the *297“police power” standard accord adequate procedural protection to “the interests of the patients.”8
With respect to the State’s parens patriae powers, the Court of Appeals accepted the District Court’s state-law distinction between patients who have and patients who have not been adjudicated incompetent. Where a patient has not been found judicially to be “incompetent” to make treatment decisions under Massachusetts law,9 the court ruled that the parens patriae interest will justify involuntary medication only when necessary to prevent further deterioration in the patient’s mental health. See id., at 660. The Court of Appeals reversed the District Court’s conclusion that a guardian must be appointed to make nonemergency treatment decisions on behalf of incompetent patients. Even for incompetent patients, however, it ruled that the State’s parens patriae interest would justify prescription only of such treatment as would be accepted voluntarily by “the individual himself . . . were he competent” to decide. Id., at 661.10 *298The Court of Appeals held that the patient’s interest in avoiding undesired drug treatment generally must be protected procedurally by a judicial determination of “incompetency.”11 If such a determination were made, further on-the-scene procedures still would be required before antipsychotic drugs could be administered forcibly in a particular instance. Ibid.12
Because the judgment of the Court of Appeals involved constitutional issues of potentially broad significance,13 we granted certiorari. Okin v. Rogers, 451 U. S. 906 (1981).
II
A
The principal question on which we granted certiorari is whether an involuntarily committed mental patient has a constitutional right to refuse treatment with antipsychotic *299drugs.14 This question has both substantive and procedural aspects. See 634 F. 2d, at 656, 661; Rennie v. Klein, 653 F. 2d 836, 841 (CA3 1981). The parties agree that the Constitution recognizes a liberty interest in avoiding the unwanted administration of antipsychotic drugs.15 Assuming that they are correct in this respect, the substantive issue involves a definition of that protected constitutional interest, as well as identification of the conditions under which competing state interests might outweigh it. See Youngberg v. Romeo, post, at 319-320; Bell v. Wolfish, 441 U. S. 520, 560 (1979); Roe v. Wade, 410 U. S. 113, 147-154 (1973); Jacobson v. Massachusetts, 197 U. S. 11, 25-27 (1905). The procedural issue concerns the minimunf procedures required by the Constitution for determining that the individual’s liberty interest actually is outweighed in a particular instance. See Parham v. J. R., 442 U. S. 584, 606 (1979); Mathews v. Eldridge, 424 U. S. 319, 335 (1976).
As a practical matter both the substantive and procedural issues are intertwined with questions of state law. In theory a court might be able to define the scope of a patient’s federally protected liberty interest without reference to state law.16 Having done so, it then might proceed to adjudicate the procedural protection required by the Due Process Clause for the federal interest alone. Cf. Vitek v. Jones, 445 *300U. S. 480, 491-494 (1980). For purposes of determining actual rights and obligations, however, questions of state law cannot be avoided. Within our federal system the substantive rights provided by the Federal Constitution define only a minimum. State law may recognize liberty interests more extensive than those independently protected by the Federal Constitution. See Greenholtz v. Nebraska Penal Inmates, 442 U. S. 1, 7, 12 (1979); Oregon v. Hass, 420 U. S. 714, 719 (1975); see also Brennan, State Constitutions and the Protection of Individual Rights, 90 Harv. L. Rev. 489 (1977). If so, the broader state protections would define the actual substantive rights possessed by a person living within that State.
Where a State creates liberty interests broader than those protected directly by the Federal Constitution, the procedures mandated to protect the federal substantive interests also might fail to determine the actual procedural rights and duties of persons within the State. Because state-created liberty interests are entitled to the protection of the federal Due Process Clause, see, e. g., Vitek v. Jones, supra, at 488; Greenholtz v. Nebraska Penal Inmates, supra, at 7, the full scope of a patient’s due process rights may depend in part on the substantive liberty interests created by state as well as federal law. Moreover, a State may confer procedural protections of liberty interests that extend beyond those minimally required by the Constitution of the United States. If a State does so, the minimal requirements of the Federal Constitution would not be controlling, and would not need to be identified in order to determine the legal rights and duties of persons within that State.
B
Roughly five months after the Court of Appeals decided this case, and shortly after this Court granted certiorari, the Supreme Judicial Court of Massachusetts announced its deci*301sion in Guardianship of Roe, 383 Mass. 415, 421 N. E. 2d 40 (1981) (Roe). Roe involved the right of a noninstitutional-ized but mentally incompetent person to refuse treatment with antipsychotic drugs. Expressly resting its decision on the common law of Massachusetts as well as on the Federal Constitution,17 Massachusetts’ highest court held in Roe that a person has a protected liberty interest in “ ‘decid[ing] for himself whether to submit to the serious and potentially harmful medical treatment that is represented by the administration of antipsychotic drugs.’” Id., at 433, n. 9, 421 N. E. 2d, at 51, n. 9.18 The court found — again apparently on the basis of the common law of Massachusetts as well as the Constitution of the United States — that this interest of the individual is of such importance that it can be overcome only by “an overwhelming State interest.” Id., at 434, 421 N. E. 2d, at 51. Roe further held that a person does not forfeit his protected liberty interest by virtue of becoming incompetent, but rather remains entitled to have his “substituted judgment” exercised on his behalf. Ibid. Defining this “substituted judgment” as one for which “[n]o medical expertise is required,” id., at 435, 421 N. E. 2d, at 52, the Massachusetts Supreme Judicial Court required a judicial determination of substituted judgment before drugs *302could be administered in a particular instance,19 except possibly in cases of medical emergency.20
C
The Massachusetts Supreme Court stated that its decision was limited to cases involving noninstitutionalized mental patients. See id., at 417, 441, 452-453, 421 N. E. 2d, at 42, 55, 61-62.21 Nonetheless, respondents have argued in *303this Court that Roe may influence the correct disposition of the case at hand.22 We agree.
Especially in the wake of Roe, it is distinctly possible that Massachusetts recognizes liberty interests of persons adjudged incompetent that are broader than those protected directly by the Constitution of the United States. Compare Roe, supra, at 434, 421 N. E. 2d, at 51 (protected liberty interest in avoiding unwanted treatment continues even when a person becomes incompetent and creates a right of incompetents to have their “substituted judgment” determined), with Addington v. Texas, 441 U. S. 418, 429-430 (1979) (because a person “who is suffering from a debilitating mental illness” is not “wholly at liberty,” and because the complexities of psychiatric diagnosis “render certainties virtually beyond reach,” “practical considerations” may require “a compromise between what it is possible to prove and what protects the rights of the individual”). If the state interest is broader, the substantive protection that the Constitution affords against the involuntary administration of anti-psychotic drugs would not determine the actual substantive rights and duties of persons in the State of Massachusetts.
Procedurally, it also is quite possible that a Massachusetts court, as a matter of state law, would require greater protection of relevant liberty interests than the minimum adequate to survive scrutiny under the Due Process Clause. Compare Roe, supra, at 434, 421 N. E. 2d, at 51 (“We have .. . stated our preference for judicial resolution of certain legal issues arising from proposed extraordinary medical treatment . . .”), with Youngberg v. Romeo, post, at 322-323 (“[T]here certainly is no reason to think judges or juries are better *304qualified than appropriate professionals in making [treatment] decisions”), and with Parham v. J. R., 442 U. S., at 608, n. 16 (Courts must not “unduly burde[n] the legitimate efforts of the states to deal with difficult social problems. The judicial model for factfinding for all constitutionally protected interests, regardless of their nature, can turn rational decisionmaking into an unmanageable enterprise”).23 Again on this hypothesis state law would be dispositive of the procedural rights and duties of the parties to this case.
Finally, even if state procedural law itself remains unchanged by Roe, the federally mandated procedures will depend on the nature and weight of the state interests, as well as the individual interests, that are asserted. To identify the nature and scope of state interests that are to be balanced against an individual’s liberty interests, this Court may look to state law. See, e. g., Roe v. Wade, 410 U. S., at 148, and n. 42, 151, and nn. 48-50; Ingraham v. Wright, 430 U. S. 651, 661-663 (1977). Here we view the underlying state-law predicate for weighing asserted state interests as being put into doubt, if not altered, by Roe.24
D
It is unclear on the record presented whether respondents, in the District Court, did or did not argue the existence of “substantive” state-law liberty interests as a basis for their *305claim to procedural protection under the federal Due Process Clause, or whether they may have claimed state-law procedural protections for substantive federal interests.25 In their brief in this Court, however, respondents clearly assert state-law arguments as alternative grounds for affirming both the “substantive” and “procedural” decisions of the Court of Appeals. See Brief for Respondents, especially at 61, 71-72, 92-95.
Until certain questions have been answered, we think it would be inappropriate for us to attempt to weigh or even to identify relevant liberty interests that might be derived directly from the Constitution, independently of state law. It is this Court’s settled policy to avoid unnecessary decisions of constitutional issues. See, e. g., City of Mesquite v. Aladdin’s Castle, Inc., 455 U. S. 283, 294 (1982); New York Transit Authority v. Beazer, 440 U. S. 568, 582-583, n. 22 (1979); Poe v. Ullman, 367 U. S. 497, 502-509 (1961); Ashwander v. TV A, 297 U. S. 288, 341, 347-348 (1936) (Brandeis, J:, concurring). This policy is supported, although not always required, by the prohibition against advisory opinions. Cf. United States v. Hastings, 296 U. S. 188, 193 (1935) (review of one basis for a decision supported by another basis not subject to examination would represent “an expression of an abstract opinion”).
*306In applying this policy of restraint, we are uncertain here which if any constitutional issues now must be decided to resolve the controversy between the parties. In the wake of Roe, we cannot say with confidence that adjudication based solely on identification of federal constitutional interests would determine the actual rights and duties of the parties before us. And, as an additional cause for hesitation, our reading of the opinion of the Court of Appeals has left us in doubt as to the extent to which state issues were argued below and the degree to which the court’s holdings may rest on subsequently altered state-law foundations.
Because of its greater familiarity both with the record and with Massachusetts law, the Court of Appeals is better situated than we to determine how Roe may have changed the law of Massachusetts and how any changes may affect this case. Accordingly, we think it appropriate for the Court of Appeals to determine in the first instance whether Roe requires revision of its holdings or whether it may call for the certification of potentially dispositive state-law questions to the Supreme Judicial Court of Massachusetts, see Bellotti v. Baird, 428 U. S. 132, 150-151 (1976).26 The Court of Appeals also may consider whether this is a case in which abstention now is appropriate. See generally Colorado River Water Conservation Dist. v. United States, 424 U. S. 800, 813-819 (1976).
The judgment of the Court of Appeals is therefore vacated, and the case is remanded for further proceedings consistent with this opinion.
So ordered.