NOTE: This is not intended as legal counsel.
When you own a business, large or small, you will likely eventually have to conduct interviews of prospective employees. Knowing what you can and can't ask can help improve the process and possibly keep you out of trouble.
Questions regarding an applicant's religious, political or ethic background are prohibited, as are questions about disabilities, sexual preferences and age.
While it's important to put your interviewee at ease, inquiring as to whether an applicant is married or has children is unacceptable; generally, questions regarding family and personal relationships are off limits. You also cannot ask if the person you're interviewing will need time off for military service or if they have been honorable discharged from service.
In some states, employers cannot ask applicants whether they've been arrested. People are sometimes arrested and later cleared of any wrongdoing. Make sure you understand what the laws are in your state before asking questions about an applicant's criminal record.
It is best to stick to questions about the job being applied for and the skills that will be required to fulfill the obligations of employment satisfactorily without getting personal in any way. Laws are strict, and it is very easy to get on the wrong side without even realizing you've done it.
Research is imperative in this type of situation. Just as in your other business facets, interviewing takes skill, and when you have to walk carefully, it is best to learn as much as possible before proceeding.