I took a listing from an owner who wants to restrict smoking in the house that he will be leasing. Can he lease his house with such a restriction?

Among other things, the Fair Housing Act prohibits discrimination in housing because of a handicap. While a smoker, as such, does not fall within a readily identifiable class of persons who have a handicap, a person who smokes or did smoke could have a respiratory or other disease which could qualify as a physical impairment under the handicap definitions in the act. While REALTORS® and the owners they represent will want to avoid advertisements or lease restrictions that exclude persons who might be handicapped, an owner should be entitled to regulate the conduct required of tenants, as long as those regulations don't otherwise violate the prohibitions of the act. Owners could advertise the property as a non-smoking facility and prohibit smoking in the premises by the terms of the lease.