Shortly after receiving Citron's report, and while the discrimination claim was still pending, Carleton was notified that the city was hiring six “permanent intermittent firefighters.” Permanent intermittent firefighters are placed on a separate reserve waiting list and hired when job openings appear, before the city consults the full civil service list.

The city approved Carleton's appointment to this position, once again subject to a successful medical examination. Carleton was again examined by the city's examiner. He was not permitted to wear his hearing aids during the hearing test, and the results of the test again placed him in Category A. Consequently, when the city presented the final list of appointments to the division, Carleton's name was not among them. The city also submitted a letter to the division making explicit that Carleton was not hired because he failed to meet the division's hearing standard.

Ultimately, Carleton's discrimination claim was considered by the Supreme Judicial Court of Massachusetts in Christopher Carleton vs. Commonwealth and Others, 447 Mass 791, 858 NE 258 (2006). The court began by examining the history of the division's hearing standard. In the mid 1980s, the statutory framework governing the civil service system gave the commonwealth's personnel administrator discretion to “establish physical requirements, in addition to those established by statute and rule, as prerequisites for appointment to any civil service position” and to “require an applicant … to submit to physical examination prior to [his or her] appointment.” The division subsequently issued guidelines concerning the rejection of candidates based on medical impairment, including deficient hearing.

In 1987, the Pension Reform Act directed the drafting of health and physical fitness standards applicable to all police officers and firefighters when they are appointed to “civil service positions.” The standards were to be rationally related to the duties of such positions and to have the purpose of minimizing health and safety risks to the public, fellow workers, and the police officers and firefighters themselves. The law made it plain that “no person appointed to a … police or firefighter position after Jan. 1, 1988, shall perform the duties of such position until he shall have undergone initial medical and physical fitness examinations and shall have met such initial standards.” The law further provided for police officers and firefighters hired after the effective date of the law to undergo periodic examinations at least every two years.

That same year, the division adopted standards “synonymous with and identical to the National Fire Protection Association's Document 1582, Medical Requirements for Firefighters.” The court noted that the NFPA is the pre-eminent fire code and standards organization in the United States and, quoting from an earlier Iowa case, that NFPA 1582 is “a standard that has been adopted by firefighting organizations throughout the United States.”

In 1995, the division began exploring the need to update its standards because of concerns that the old ones “no longer represented the latest research of the relationship between medical conditions and categories and actual job performance” and “needed revision to keep pace with developing case law around the Americans with Disabilities Act.” The resulting new standards divided medical deficiencies into two categories: Category A and Category B. Neither a candidate nor current firefighter could be certified as meeting the medical requirements of the standard if a physician determined that the candidate had any Category A medical condition. If a person had a Category B medical condition, he or she could not be certified as meeting the medical requirements of the standard only if the physician determined that the condition was of sufficient severity to prevent the person from performing the essential functions of a firefighter without posing a significant risk to the safety and health of him- or herself or others.