Police power and qualifications

The private employer may likewise fix standards and tests, but, if his business is one in which the public health or safety is concerned, the state may legislate so as to exclude from work in such private calling those whose incompetence might cause injury to the public. But, as the public interest is the basis of such legislation, the tests and prohibition should be enacted with reference to that object, and so as not unduly to 'interfere with private business, or impose unusual and unnecessary restrictions upon lawful occupations.