Must we give rejected applicant a copy of a negative reference letter?

Q. We request references from applicants’ former or current employers. Recently, an applicant (who was not hired) requested a copy of his former employer’s reference letter, which indicated that the applicant was difficult to work with and performed poorly. The letter was one of the factors considered when we decided not to hire him. Must we turn over the letter (or any other part of our file on the applicant)? ...