Section 18 of the Home Rule Act
Section 18 of the Home Rule Act, provides in full text:
No city shall exercise any powers or authority beyond the city limits except such as are conferred by an act of the General Assembly, and no city shall engage in any proprietary or private business except as authorized by the General Assembly. Notwithstanding the grant of powers contained in this act, no city shall exercise powers contrary to, or in limitation or enlargement of, powers granted by acts of the General Assembly which are--
(a) Applicable to a class or classes of cities on the following subjects:
(1) Providing for the filing and collection of municipal and tax claims or liens and for the sale of real or personal property in satisfaction thereof;
(2) Providing for the exercise of the power of eminent domain and the procedure for the condemnation of property for public purposes;
(3) Providing for the assessment of damages and benefits for property taken, injured or destroyed;
(4) Providing methods for the incurring or increasing of indebtedness;
(5) Providing for the annexation or exclusion or detachment of territory;
(6) Regulating public schools;
(7) Providing for the personal registration of electors;
(8) Limiting rates and fixing subjects of taxation;
(9) Providing for the assessment of real or personal property and persons for taxation purposes.
(b) Applicable in every part of the Commonwealth.
(c) Applicable to all the cities of the Commonwealth, including, but not limited to, those acts providing for the disability compensation of police officers and firefighters.