We have your request to he advised as to the interpretation of section 308 of the Mental Health Act of July 11, 1923, P. L. 998, as amended by the Act of May 28, 1937 (no. 287), with respect to the following questions:
1. Do the provisions of the amendatory act, which in effect release counties from paying full per capita cost of patients maintained in State mental institutions, except where such patients are undergoing sentence, apply only to patients committed after the effective date of such act, or to all patients?
2. Are the counties liable for the full per capita cost of patients in State mental institutions until the effective date of the amendatory act where such patients, although not actually serving sentence when committed, were at that time, and under the. provisions of the act before amendment, properly classified so as to impose upon the counties the full per capita rate?
Section 308 of the act, as amended provides, inter alia:
“The expense of examination, including the fees of physicians or commissioners, and all costs incident to, [such removal] the commitment and transfer of such person, and if such person is undergoing sentence, all costs of maintenance in the hospital previous to the expiration of such sentence, shall be paid by the county liable for the maintenance of the patient in the prison, penitentiary, reformatory, or other penal or correctional institution *22from which he was [removed] transferred, without recourse against any poor district.”
Section 507, which is corollary to the section just quoted, provides:
“The expenses of the care and maintenance, including clothing in any mental hospital of an insane [prisoners] or mentally defective person undergoing sentence for a criminal offense shall be paid [in the same manner as the costs of commitment of such prisoner, as provided in section five hundred and two of this act] by the county liable for the maintenance of the patient in the prison, penitentiary, reformatory, or other penal or correctional institution from which he was transferred. Provided, That if the term of sentence of any prisoner shall expire while he is still a patient in any hospital, such expenses shall thereupon become chargeable as provided in section five hundred and three of this act.”
The material included in brackets was deleted from, and the material in italics was inserted in, the original statute by the provisions of the amendatory act. Such amendatory act by its terms became effective June 1,1937.
The act defines the liability of counties for the maintenance of persons in State mental institutions. There is nothing in either section referred to, or in any other part of the amendatory act, which restricts the provisions thereof to patients who may be committed in the future. The language of the act applies to all patients and defines the liability as to them from the effective date of the act forward. Accordingly, patients in mental institutions on the effective date of the act who were committed while serving sentence, while sentence has not yet expired, must be maintained wholly by the counties until the expiration of their sentences. Conversely, patients in mental institutions who have heretofore been maintained wholly by the counties but who were not serving sentence when committed are not chargeable to the counties at the full per capita rate after the effective date of *23the amendatory act. As to such patients the amendatory act redefines the future liability of the counties.
From the foregoing it necessarily follows that where the maintenance of patients under the original act has been properly charged to the counties at the full per capita cost the liability of the counties to pay such full per capita cost continues until the effective date of the amendatory act, even if, under the provisions of such act, such patients will not be charged to the counties at the full per capita rate in the future. The amendatory act cannot be applied retroactively to define or limit the liability of the counties prior to its effective date because legislation which affects substantive rights will not be construed to be retroactive: Kuca v. Lehigh Valley Coal Co., 268 Pa. 163.
Therefore, we advise you that:
1. The provisions of the amendatory Act of May 28, 1937, which in effect release counties from paying full per capita cost of patients maintained in State mental institutions, except where such patients are undergoing sentence, apply not only to patients committed after the effective date of such act but to all patients.
2. The counties are liable for the full per capita cost of patients in State mental institutions until the effective date of said amendatory act where such patients, although not actually serving sentence when committed, were, at that time, and under the provisions of the act before amendment, properly classified so as to impose upon the counties the full per capita rate.