This is a "cut to the chase" type of question and is an extremely important part of the interview. An ill-conceived or unpracticed response here in particular could set you back considerably in the eyes of the interviewer. They basically want to know that you know the guidelines and restrictions of the Fair Debt Collection Practices Act. They want to understand what knowledge you've gained about this critical part of the job. Being confident and being able to convey that you know what you're doing allows the interviewer to picture you at their company doing their bill and account collection. Be clear, be thorough and keep building your case.