The principal author of this guide is James J. Dietrich, who worked earnestly to identify available resources regarding horizontal gaze nystagmus. Jim undertook this task in his position as staff attorney with the American Prosecutors Research Institute's (APRI) National Traffic Law Center (NTLC). Janice Frost, NTLC's senior attorney, contributed her trial expertise in compiling sample predicate questions for this guide to assist prosecutors in preparing cases with HGN issues. The final publication is the result of a collaborative process which drew on the knowledge, expertise and patience of many persons, particularly NTLC's Director, Patricia Gould, NTLC's Staff Attorney, Penney Azcarate, NTLC's Administrative Assistants, Alexia L. Williams and Ruth R. Sanderlin, and APRI's Director of Management and Development, Heike P. Gramckow.

The authors sincerely appreciate the efforts of those who volunteered their time and energy to review and critique this guide before it went to final print. Those persons are: