Rejecting applicants based on an "all entries" approach to their criminal background could be considered arbitrary discrimination. To stay on the right side of the law, you must show that the past crime affects the applicant's ability to meet the tenancy obligations or presents a direct threat to the health and safety of other residents.
"Individuals like you who have successfully completed a drug treatment program are protected under the disability provisions of the Fair Housing Act. This means that a landlord cannot refuse to rent to you solely because of a history of drug addiction, since you are in recovery. Your history of abusing drugs in the past may not be an accurate measure of your current ability to be a good tenant."