Code of Conductbackflow symbol

Backflow testers should be required to sign a Code of Conduct document.
A few samples of these documents can be found here:

Orange County, California, Health Care Agency
Mesa Consolidated Water District
Georgia Fraudulent Tester Guideline
Georgia Code of Ethics
City of Irving Backflow Tester Registration Form
Code of Conduct Samples in MS Word format

Certified testers placed on an approved testers list by the local authority should have their credentials checked, obtain a business license, have insurance coverage, and sign a Code of Conduct document.

The local authority should be comfortable that the tester requesting placement on the approved list is a competent tester. Some authorities will require the applicant take a local examination. Not all training facilities teach the same information or require that the tester actually learn the field test procedures to be certified.

It is highly recommended that the local authority create a Code of Conduct for the certified tester to sign. A certified tester who is placed on a list of approved testers that is sent to the customer is a contractor representing the local authority. Testers who do not provide good service to the customers should be removed from the approval list.

This information taken from "Backflow Prevention, Theory and Practice" 2nd Edition