A liaison officer is basically the "go-between" or "middle man" for two entities, whether those entities are the public and a corporation, or an incident and a group of people. Oftentimes a liaison officer is hired as the middle person between agency representatives and a group monitoring incident status, and sometimes the liaison officer is the middle person between tenants and landlords.
One of the first duties of a liaison officer when regarding an incident is to check in with the incident command post, the base or base camps or the staging areas if applicable.
A liaison officer is responsible for many tasks after the initial check-in or orientation of the situation. Other duties include: acquire work materials, organize and brief any potential subordinates, receive briefing from immediate supervisor, if applicable, and complete any forms or documentation.
Common duties of a liaison officer in any capacity include: assist in the preparation of weekly and monthly reports, liaise with other disciplines for coordination efforts, initiate and generate technical instructions, deal with any "people" issues in a positive manner, respond to complaints and address concerns and work to establish accommodation needs.
Many cities in the U.S. hire a liaison officer to work within a city department. An example is the Community Liaison Officer position with the City of St. Paul, Minnesota. Job duties of this liaison officer position include: directing calls and walk-ins to correct personnel, explaining police procedures and protocols to the public (serving as "go-between" or "middle man" to the public), assisting police and neighborhood residents and performing daily maintenance of police vehicles.