Hiring persons based on whether they are men or women is unlawful. Assuming that women cannot perform the duties of a job should be avoided. Instead, women should be allowed to prove they can perform the duties of the position.
Any information about an applicants origin should not be asked for. This includes information about applicant's place of birth, or spouse.
A judgment can be made on a conviction record other than an arrest record, because a conviction is an indication of guilt. Although, if you are hiring a person to park cars, a conviction of grand theft auto would be relevant, whereas a failure to pay rent that was brought to court would not be relevant.
Questions about an applicants age or date of birth should be avoided. However the question may be used to retrieve information to comply with the child labor law. For example - "Are you under 18?"
Discrimination based on pregnancy or childbirth is illegal. Questions regarding family plans, and birth control techniques can also be discriminatory because they are not also asked to men.