OPINION OF THE COURT
The sole issue on appeal is whether the immunity provisions of the Mental Health Procedures Act, 50 P.S. § 7101, et seq., apply to hospitals and doctors who provide medical care to a mentally ill patient pursuant to a contract with a mental hospital. Because we hold that the immunity provisions of the Mental Health Procedures Act apply to doctors and hospitals in such a situation, we reverse the order of the Superior Court and reinstate the order of the trial court entering judgment in favor of appellants on the verdict of the jury.
The relevant facts are that on August 11, 1980, appellee Anne L. Allen (“the patient”) was admitted for in-patient treatment at Norristown State Hospital for treatment of mental retardation and psychosis after she suffered an adverse reaction to her medication that made it difficult for her *302parents to control her behavior. On November 30, 1982, the patient was transferred to Montgomery Hospital for treatment of certain physical ailments pursuant to a contractual agreement through which Montgomery Hospital would provide medical treatment for mental patients from Norristown State Hospital. Dr. Paul Casey, Jr., was the patient’s attending physician at Montgomery Hospital. The initial diagnosis was that the patient was suffering from dehydration and a fever. The patient was admitted to a private room on the orthopedic floor of Montgomery Hospital.
Suspecting the patient’s physical problems were caused by a reaction to medication prescribed for her mental problems, Dr. Casey removed the patient from all but one of her prescribed psychotropic drugs. While hospitalized at Montgomery Hospital, the patient was kept in a posey vest restraint.1 A posey restraint had also been employed to secure the patient at Norristown State Hospital in the weeks prior to her transfer to Montgomery Hospital. The patient’s physical condition improved following her treatment and she was scheduled to be returned to Norristown State Hospital on December 6, 1982. However, on December 5, 1982 at 2:00 a.m., a nurse at Montgomery Hospital discovered the patient hanging about six (6) inches above the floor between the side-rails and her bed with the posey restraint around her neck. The patient had managed to free one arm from the restraint and had apparently attempted to get out of the bed. The nurse called for aid in freeing the patient from the restraint and administered cardio-pulmonary resuscitation. The patient survived but tragically suffered permanent brain damage due to lack of oxygen.
On November 11, 1984, the patient’s parents filed a complaint against Montgomery Hospital and Dr. Casey (collectively, the “appellants”) for medical negligence.2 Appellants filed *303a Motion in Limine requesting that the immunity provisions of the Mental Health Procedures Act (MHPA), 50 P.S. § 7101, et seq., be applied to the proceedings. Specifically, appellants claimed that they were immune from liability under Section 114 of the MHPA, 50 P.S. § 7114, unless their actions in treating the patient were found to constitute willful misconduct or gross negligence. The trial court granted the motion and certified the issue for interlocutory appeal to the Superior Court. However, the Superior Court declined to accept the appeal, and this Court denied allocatur. 530 Pa. 659, 609 A.2d 167 (1992).
The case then proceeded to trial, and the jury was instructed, pursuant to the MHPA, that a verdict could only be entered in favor of appellees if the jury found that appellants’ actions in treating the patient amounted to gross negligence.3 The jury returned a verdict in favor of appellants because it found that neither of appellants were grossly negligent in their treatment of the patient. Appellees filed post-trial motions which were denied. Appellees then filed a timely appeal. On December 19, 1995, a three judge panel of the Superior Court, with one judge dissenting, reversed and remanded the matter for a new trial because it held that the trial court erred in determining that the immunity provisions of the MHPA applied.4 On May 29, 1996, we granted allocatur in order to *304decide if the immunity provision found in Section 114 of the MHPA, 50 P.S. § 7114, applies to physicians and doctors and hospitals who provide medical care for a physical ailment to a mental patient pursuant to a contract with a mental health care facility.
Appellees argue that Section 114 of the MHPA does not provide appellants with immunity because it only applies to treatment which is specifically directed to treating the patient’s mental illness and not to treatment for physical ailments. Appellants, however, argue that the immunity provision of the MHPA applies to hospitals and doctors who provide medical care for physical ailments to mental patients pursuant to a contract with a mental health facility. Our determination of which interpretation is correct depends upon our analysis of the controlling statutory language.
When reviewing a statute, we are guided by the Statutory Construction Act. See 1 Pa.C.S. § 1501 et seq. The object of all statutory interpretation is to ascertain and effectuate the intention of the General Assembly. 1 Pa.C.S. § 1921(a). When ascertaining the legislative intent, it is presumed that the General Assembly did not intend a result that is absurd, impossible of execution or unreasonable. Also, if possible, the statute must be construed to give effect to all of its provisions. Id. Moreover, the provisions of a statute must be liberally interpreted to effect its object and to promote justice. 1 Pa.C.S. § 1928(b) (providing that statutes which do not fall within the classes of statutes established in subsection (b), none of which apply here, shall be liberally construed).5
*305In 1976, the General Assembly enacted the MHPA to provide procedures and treatment for the mentally ill in this Commonwealth. The policy of the MHPA is set forth in Section 102, which provides, in pertinent part:
[I]t is the policy of the Commonwealth of Pennsylvania to seek to assure the availability of adequate treatment to persons who are mentally ill, and it is the purpose of this act to establish procedures whereby this policy can be effected. The provisions of this act shall be interpreted in conformity with the principles of due process to make voluntary and involuntary treatment available where the need is great and its absence could result in serious harm to the mentally ill person or to others. Treatment on a voluntary basis shall be preferred to involuntary treatment; and in every case, the least restrictions consistent with adequate treatment shall be employed.
50 P.S. § 7102.
Consistent with this policy to insure adequate treatment to mentally ill individuals in the least restrictive environment, the MHPA provides civil and criminal immunity for decisions regarding the treatment of the patient absent willful misconduct and/or gross negligence. Farago v. Sacred Heart General Hospital, 522 Pa. 410, 414, 562 A.2d 300, 302 (1989). The relevant statutory language regarding this immunity is found in Section 114 of the MHPA and provides, in pertinent part, that:
[I]n the absence of willful misconduct or gross negligence, a county administrator, a director of a facility, a physician, a peace officer, or any other authorized person who participates in a decision that a person be examined or treated under this act, or that the person be discharged, or placed *306under partial hospitalization, outpatient care or leave of absence, or that the restraint upon such person be reduced, or a county administrator or person who denies an application for voluntary treatment or for involuntary emergency examination and treatment, shall not be civilly or criminally liable for such decision or for any of its consequences.
50 P.S. § 7114(a) (emphasis added). Montgomery Hospital is a person within the meaning of this section. Farago, supra at 419, 562 A.2d at 303 (hospital qualifies as person subject to immunity under Section 114 of the MHPA). Thus, if appellants participated in the decision to provide treatment to the patient under the MHPA, the immunity provision of Section 114 of the MHPA applies to them.
Section 114 of the MHPA does not specifically define what is encompassed within the term “treated.” However, definitions of “treatment” and “adequate treatment” can be found elsewhere in the MHPA. In particular, the MHPA provides as follows:
Adequate treatment means a course of treatment designed and administered to alleviate a person’s pain and distress and to maximize the probability of his recovery from mental illness. It shall be provided to all persons in treatment who are subject to this act. It may include inpatient treatment, partial hospitalization, or outpatient treatment. Adequate inpatient treatment shall include such accommodations, diet, heat, light, sanitary facilities, clothing recreation, education and medical care as are necessary to maintain decent, safe and healthful living conditions.
Treatment shall include diagnosis, evaluation, therapy, or rehabilitation needed to alleviate pain and distress and to facilitate the recovery of a person from mental illness and shall also include care and other services that supplement treatment and aid or promote such recovery.
50 P.S. § 7104 (Provision for Treatment) (emphasis added).
The above provisions demonstrate a clear public policy by the General Assembly to make adequate treatment available to mentally ill patients with the least restrictions to their *307person. Moreover, as is evident from the General Assembly’s definition of “adequate treatment” and “treatment” in the MHPA, the General Assembly did not intend to limit treatment to that only directly related to a patient’s mental illness. Instead, treatment is given a broader meaning in the MHPA to include medical care coincident to mental health care. Medical care is commonly understood to include the prevention or alleviation of both physical and mental illness. See 1 Pa.C.S. § 1903(a) (courts must construe statutory terms not defined in statute in accordance with their common usage). Also, treatment under the MHPA broadly includes “care and other services that supplement treatment” in order to promote the recovery of the patient from mental illness. Therefore, applying the rules of statutory construction to the immunity provision of Section 114 of the MHPA, we conclude that the General Assembly decided to ameliorate certain risks by granting limited immunity to doctors and hospitals who have undertaken the treatment of the mentally ill, including treatment for physical ailments pursuant to a contract with a mental health facility to provide such treatment.
Policy reasons also support this interpretation of the immunity provision in Section 114 of the MHPA. If the provision were interpreted narrowly such as urged by appellees so that it only applied to treatment specifically directed at a mental illness, it could reduce or eliminate the willingness of doctors or hospitals to provide needed medical care to a mentally ill patient who is referred by a mental hospital for medical treatment. Even if doctors or hospitals still provided treatment for physical ailments in such a situation, it could lead such providers of medical care to minimize their risks by placing the mentally ill patients in a more restrictive environment than is necessary or adopting other precautionary measures which would increase the costs of the medical care provided to the mentally ill. Such a narrow interpretation would clearly contravene the purposes of the MHPA to provide adequate treatment to the mentally ill with the least *308restrictive physical restraints.6
Applying this interpretation to the present case, the patient was admitted to Montgomery Hospital in 1982 pursuant to an agreement with Norristown State Hospital. At that time, the patient was mentally ill and was in acute need of medical care. The care provided by appellants was medical care designed to “facilitate the recovery of a person from mental illness” under 50 P.S. § 7104. Because appellants provided such treatment, the trial court correctly instructed the jury that appellants were entitled to invoke the immunity provision of Section 114 of the MHPA unless their actions in treating the patient constituted gross negligence.7
Accordingly, the order of the Superior Court is reversed and the order of the trial court entering judgment for appellants on the verdict of the jury is reinstated.
. A posey restraint is a vest-like restraint which is tied to the patient’s bed in order to keep the patient from falling out of bed, but which allows the patient to move his or her arms and to sit up in bed.
. Several distributors of posey restraints were also initially named as defendants, but summary judgment was entered in their favor prior to *303trial. Norristown State Hospital was joined as an additional defendant by Montgomery Hospital, but non-suit was entered in favor of Norris-town State Hospital following the close of appellees’ case.
. Appellees’ complaint never alleged that appellants' actions amounted to willful misconduct. Thus, the trial court did not mention willful misconduct when instructing the jury on the immunity provision in Section 114 of the MHPA.
. The majority of the Superior Court reached its decision by recognizing that the immunity provisions of the MHPA have only been applied to psychiatrists and no other medical care providers. Also, the majority found that the immunity provisions of the MHPA have never been applied to anyone, including psychiatrists, for treating a mentally ill patient for a physical ailment. Moreover, the majority found that psychiatrists only have received immunity under the MHPA when the issue involves the level of supervision or restraint necessary to protect the patient. Therefore, the majority reasoned that appellants here were not entitled to immunity because they provided care for a physical *304ailment rather than a mental illness and the claims raised did not involve the restraints used or supervision supplied to the patient.
The dissent, however, would have applied the immunity provisions of the MHPA. In doing so, the dissent argued that mental illness is often manifested from physical problems. Also, the patient’s physical ailments and mental illness were both treated by appellants. Moreover, the dissent believed that the proper focus in analyzing such an issue should be on whether the treatment administered to the mentally ill patient falls within the scope of conduct for which immunity is granted.
. The Superior Court has strictly construed certain provisions of the MHPA which concern the deprivation of a liberty interest or a privacy right. See In re S.C., 280 Pa.Super. 539, 421 A.2d 853 (1980) (involun*305tary commitment pursuant to 50 P.S. § 7303(b) implicated a liberty interest requiring strict construction of that section); In the Interest of Roy, 423 Pa.Super. 183, 620 A.2d 1172 (1993), appeal denied, 536 Pa. 644, 639 A.2d 30 (1994) (50 P.S. § 7111, which relates to confidentiality of patient's records, must be strictly construed). This Court, however, employed a liberal construction in Farago v. Sacred Heart General Hospital, 522 Pa. 410, 562 A.2d 300 (1989), when determining that hospitals were a person covered by the immunity provision of Section 114 of the MHPA.
. We note that the dissenting opinion agrees with the narrow position taken by the appellees. However, like the appellees, the dissenting opinion ignores the policy behind the MHPA. Also, the dissenting opinion ignores the language of the MHPA which extends limited immunity to doctors and hospitals who provide "treatment" to mentally ill patients and "treatment” within the plain language of the MHPA is given a broad meaning to include medical care for physical ailments as well as mental health care.
. Appellees, in their appellate brief, argue that the broad interpretation of the immunity provision of Section 114 of the MHPA which we take today would unconstitutionally deny equal protection to the mentally'ill by denying them redress in the courts. It is presumed that the General Assembly does not intend to violate the United States or Pennsylvania Constitutions and any doubts are to be resolved in favor of finding the statute constitutional. 1 Pa.C.S. § 1922(3); Jenkins v. Hospital of the Medical College of Pennsylvania, 535 Pa. 252, 262, 634 A.2d 1099, 1104 (1993). Equal protection does not prohibit a state from classifying persons differently and treating the classes differently. James v. Southeastern Pennsylvania Transportation Authority, 505 Pa. 137, 477 A.2d 1302 (1984).
Appellees’ brief fails to demonstrate how Section 114 of the MHPA is unconstitutional. The mentally ill require more specialized or intensive care than the non-mentally ill. In order to protect the mentally ill and provide them with adequate treatment in the least restrictive manner, ■ the General Assembly enacted the MHPA. Absent willful misconduct or gross negligence, the General Assembly provided immunity to health care providers of the mentally ill in order to ensure that this important government interest is met. Thus, the limited restriction on the right to sue in the MHPA bears a reasonable relation to a substantial government interest.