53 Pa. Stat. § 23444
The following positions shall be included in the exempt class:--
First.--The superintendent of police and detectives, and the chief of the first department.
Second.--One secretary and one confidential clerk of the mayor, and one confidential clerk to the director of each executive department.
Third.--In addition to the above, there may be included in the exempt class other offices or positions, except laborers, for the filling of which competitive or non-competitive examinations shall be found by the civil service commission to be impracticable. But no office or position shall be deemed to be in the exempt class unless it is specifically named in such class in the rules; and the reason for each such exemption shall be stated, separately, in the annual reports of the said commission. Not more than one appointment shall be made to, or under the title of, any such office or position, unless a different number is specifically mentioned in the rules. No office or position shall be classified by the commission in the exempt class, except after public hearing by the commission, or any member thereof. Suitable public notice of such hearing shall be given by the said commission. At any such hearing any taxpayer of the city shall have the right to be heard, either in person or by counsel, either in opposition to or in favor of the proposed exemption. Appointments in the exempt class may be made without examination.
53 P.S. § 23444