Since childhood, Christopher Carleton has suffered “bilateral mild to moderately severe sensorineural hearing loss,” meaning he lacks the necessary amplification to hear within a normal decibel range. To correct this deficiency, he has worn hearing aids in both ears from a very early age. Nonetheless, he has had significant contact with the fire service since the age of 17.

In 1997, he participated in a volunteer program sponsored by the Northborough (Mass.) Fire Department and the Boy Scouts. He took part in “all aspects of firefighting, except those involving entrance to burning structures.” He “received regular on-the-job firefighting training at weekly meetings.” He learned to operate fire ladders and fire hoses; was taught proper drafting techniques; and practiced using hydrants, driving fire vehicles, setting up lighting and fans on the fireground, assisting with the rehabilitation of firefighters, and assisting with salvage operations.

In 1998, Carleton earned his EMT license and began working intermittently for two private ambulance companies. In October 1999, he was hired as a 911 emergency dispatcher. In none of these activities was there ever a problem reported regarding his hearing or ability to communicate with others.

In addition, Carleton served as a “call” firefighter for the town of Stowe from January 2000 until 2002, successfully completing the Firefighter I certification course. This course included three days of “structural firefighting inside a burning structure and outside on the fireground adjacent thereto.” During those exercises, Carleton wore his hearing aids as well as head coverings and other equipment. Despite sweating, being sprayed intermittently with water and being exposed to significantly loud background noise, Carleton had no problem hearing or communicating with others, and his hearing aids functioned properly at all times.

On April 29, 2000, Carleton took the firefighter civil service examination and scored 99 out of a possible 100, placing his name close to the top of the civil service list. In April 2001, when he was notified that the City of Marlborough would be hiring two firefighters, he immediately informed the city that he would like to be considered for the position. Thereafter, he was scheduled for a pre-employment medical examination.

Because the city is a municipality within the civil service system, it is required to adhere to statewide minimum health and fitness standards for police officers and firefighters promulgated by the state division of human resources. At the time Carleton applied for a firefighting position with the city, the standard contained a maximum hearing deficiency threshold. If the applicant's hearing deficiency exceeded this threshold, he was deemed to have a “Category A” medical condition, which is considered incompatible with the performance of the essential job functions of a municipal firefighter and leads to the applicant's disqualification.