The Commission may refuse to examine or, if examined, may refuse
to certify any applicant who is physically or mentally unfit to perform
the full duties of the position applied for, or who is an habitual
substance abuser, or who is guilty of any crime involving moral turpitude,
or who has engaged in infamous or notoriously disgraceful conduct,
or who has been dismissed from public service for delinquency or misconduct
in office, or who is affiliated with any group whose policies or activities
are subversive to the forms of government set forth in the constitutions
and laws of the United States and the Commonwealth of Pennsylvania.