Opinion of the Court his interest in avoiding involuntary administration of antipsychotic drugs was protected under the Fourteenth Amendment's Due Process Clause. "The forcible injection of medication into a nonconsenting person's body," we said, "represents a substantial interference with that person's liberty." Id., at 229. In the case of antipsychotic drugs like Mellaril, that interference is particularly severe: "The purpose of the drugs is to alter the chemical balance in a patient's brain, leading to changes, intended to be beneficial, in his or her cognitive processes. While the therapeutic benefits of antipsychotic drugs are well documented, it is also true that the drugs can have serious, even fatal, side effects. One such side effect identified by the trial court is acute dystonia, a severe involuntary spasm of the upper body, tongue, throat, or eyes. The trial court found that it may be treated and reversed within a few minutes through use of the medication. Cogentin. Other side effects include akathesia (motor restlessness, often characterized by an inability to sit still); neuroleptic malignant syndrome (a relatively rare condition which can lead to death from cardiac dysfunction); and tardive dyskinesia, perhaps the most discussed side effect of antipsychotic drugs. Tardive dyskinesia is a neurological disorder, irreversible in some cases, that is characterized by involuntary, uncontrollable movements of various muscles, especially around the face. . . . [T]he proportion of patients treated with antipsychotic drugs who exhibit the symptoms of tardive dyskinesia ranges from 10% to 25%. According to the American Psychiatric Association, studies of the condition indicate that 60% of tardive dyskinesia is mild or minimal in effect, and about 10% may be characterized as severe." Id., at 229-230 (citations omitted). Taking account of the unique circumstances of penal confinement, however, we determined that due process allows a Opinion of the Court mentally ill inmate to be treated involuntarily with antipsychotic drugs where there is a determination that "the inmate is dangerous to himself or others and the treatment is in the inmate's medical interest." Id., at 227. Under Harper, forcing antipsychotic drugs on a convicted prisoner is impermissible absent a finding of overriding justification and a determination of medical appropriateness. The Fourteenth Amendment affords at least as much protection to persons the State detains for trial. See Bell v. Wolfish, 441 U. S. 520, 545 (1979) ("[P]retrial detainees, who have not been convicted of any crimes, retain at least those constitutional rights that we have held are enjoyed by convicted prisoners"); O'Lone v. Estate of Shabazz, 482 U. S. 342, 349 (1987) ("[P]rison regulations . . . are judged under a 'reasonableness' test less restrictive than that ordinarily applied to alleged infringements of fundamental constitutional rights"). Thus, once Riggins moved to terminate administration of antipsychotic medication, the State became obligated to establish the need for Mellaril and the medical appropriateness of the drug. Although we have not had occasion to develop substantive standards for judging forced administration of such drugs in the trial or pretrial settings, Nevada certainly would have satisfied due process if the prosecution had demonstrated, and the District Court had found, that treatment with antipsychotic medication was medically appropriate and, considering less intrusive alternatives, essential for the sake of Riggins' own safety or the safety of others. See Harper, supra, at 225-226; cf. Addington v. Texas, 441 U. S. 418 (1979) (Due Process Clause allows civil commitment of individuals shown by clear and convincing evidence to be mentally ill and dangerous). Similarly, the State might have been able to justify medically appropriate, involuntary treatment with the drug by establishing that it could not obtain an adjudication of Riggins' guilt or innocence by using less intrusive means. See Illinois v. Allen, 397 U. S. 337, 347 Opinion of the Court (1970) (Brennan, J., concurring) ("Constitutional power to bring an accused to trial is fundamental to a scheme of ‘ordered liberty' and prerequisite to social justice and peace"). We note that during the July 14 hearing Riggins did not contend that he had the right to be tried without Mellaril if its discontinuation rendered him incompetent. See Record 424-425, 496, 500. The question whether a competent criminal defendant may refuse antipsychotic medication if cessation of medication would render him incompetent at trial is not before us. Contrary to the dissent's understanding, we do not "adopt a standard of strict scrutiny." Post, at 156. We have no occasion to finally prescribe such substantive standards as mentioned above, since the District Court allowed administration of Mellaril to continue without making any determination of the need for this course or any findings about reasonable alternatives. The court's laconic order denying Riggins' motion did not adopt the State's view, which was that continued administration of Mellaril was required to ensure that the defendant could be tried; in fact, the hearing testimony casts considerable doubt on that argument. See supra, at 130-131. Nor did the order indicate a finding that safety considerations or other compelling concerns outweighed Riggins' interest in freedom from unwanted antipsychotic drugs. Were we to divine the District Court's logic from the hearing transcript, we would have to conclude that the court simply weighed the risk that the defense would be prejudiced by changes in Riggins' outward appearance against the chance that Riggins would become incompetent if taken off Mellaril, and struck the balance in favor of involuntary medication. See Record 502 ("[T]hat he was nervous and so forth... can all be brought out [through expert testimony]. And when you start weighing the consequences of taking him off his medication and possibly have him revert into an incompetent situation, I don't think that that is a good exper Opinion of the Court iment"). The court did not acknowledge the defendant's liberty interest in freedom from unwanted antipsychotic drugs. This error may well have impaired the constitutionally protected trial rights Riggins invokes. At the hearing to consider terminating medication, Dr. O'Gorman suggested that the dosage administered to Riggins was within the toxic range, id., at 483, and could make him "uptight," id., at 484. Dr. Master testified that a patient taking 800 milligrams of Mellaril each day might suffer from drowsiness or confusion. Id., at 416. Cf. Brief for American Psychiatric Association as Amicus Curiae 10-11 ("[I]n extreme cases, the sedationlike effect [of antipsychotic medication] may be severe enough (akinesia) to affect thought processes"). It is clearly possible that such side effects had an impact upon not just Riggins' outward appearance, but also the content of his testimony on direct or cross examination, his ability to follow the proceedings, or the substance of his communication with counsel. Efforts to prove or disprove actual prejudice from the record before us would be futile, and guesses whether the outcome of the trial might have been different if Riggins' motion had been granted would be purely speculative. We accordingly reject the dissent's suggestion that Riggins should be required to demonstrate how the trial would have proceeded differently if he had not been given Mellaril. See post, at 149-150. Like the consequences of compelling a defendant to wear prison clothing, see Estelle v. Williams, 425 U.S. 501, 504-505 (1976), or of binding and gagging an accused during trial, see Allen, supra, at 344, the precise consequences of forcing antipsychotic medication upon Riggins cannot be shown from a trial transcript. What the testimony of doctors who examined Riggins establishes, and what we will not ignore, is a strong possibility that Riggins' defense was impaired due to the administration of Mellaril. We also are persuaded that allowing Riggins to present expert testimony about the effect of Mellaril on his de KENNEDY, J., concurring in judgment meanor did nothing to cure the possibility that the substance of his own testimony, his interaction with counsel, or his comprehension at trial were compromised by forced administration of Mellaril. Even if (as the dissent argues, post, at 147-149) the Nevada Supreme Court was right that expert testimony allowed jurors to assess Riggins' demeanor fairly, an unacceptable risk of prejudice remained. See 107 Nev., at 181, 808 P. 2d, at 537-538. To be sure, trial prejudice can sometimes be justified by an essential state interest. See Holbrook v. Flynn, 475 U. S. 560, 568-569 (1986); Allen, supra, at 344 (binding and gagging the accused permissible only in extreme situations where it is the "fairest and most reasonable way" to control a disruptive defendant); see also Williams, supra, at 505 (compelling defendants to wear prison clothing at trial furthers no essential state policy). Because the record contains no finding that might support a conclusion that administration of antipsychotic medication was necessary to accomplish an essential state policy, however, we have no basis for saying that the substantial probability of trial prejudice in this case was justified. The judgment of the Nevada Supreme Court is reversed, and the case is remanded for further proceedings not inconsistent with this opinion. It is so ordered. JUSTICE KENNEDY, concurring in the judgment. The medical and pharmacological data in the amicus briefs and other sources indicate that involuntary medication with antipsychotic drugs poses a serious threat to a defendant's right to a fair trial. In the case before us, there was no hearing or well-developed record on the point, and the whole subject of treating incompetence to stand trial by drug medication is somewhat new to the law, if not to medicine. On the sparse record before us, we cannot give full consideration to the issue. I file this separate opinion, however, to express |