These standards took effect in 1997 and were still operative in 2001 when Carleton was first denied employment. These standards didn't allow an applicant to overcome the Category A classification by using hearing aids.

The division once more began considering revisions to its standards in 2001 based on an updated job task analysis report. This revision process included the selection of a new expert panel in the fields of vision and hearing. The panel agreed that an “adequate ability to hear is critical for communicating effectively as a police officer or firefighter.” It further said that “firefighters are more likely to experience problems with hearing aids during the performance of their duties at the fire scene. A hearing aid can fail due to being soaked or from excessive perspiration, preventing the wearer from performing a critical job function during the failure. It is possible that the failure could occur during a circumstance that is life-threatening. Police officers are not likely to encounter these types of conditions while performing their normal work duties.”

Based on these findings, the panel recommended that police officer candidates be permitted to use hearing aids to meet the hearing standard, but that firefighter candidates not be permitted to do the same unless the hearing aids used were implantable. (Implantable hearing aids are not, for all practical purposes, presently available.)

The panel also agreed that localization of sound (determining where it is coming from) “is not critical for policing or firefighting because the equipment and other background noise can hinder [the] ability to do so, and other cues can be used.” It further found that “hearing loss in firefighters is … common over time;” that “many incumbents are able to continue to perform their work, even with impaired hearing;” and that “there is little evidence that modest hearing loss is incompatible with safe performance of essential job functions.”

The revision process culminated in 2003 with the adoption of new standards, including revisions to the hearing standard. Consequently, although the new hearing standard contains a Category A hearing deficiency threshold, an applicant assessed with a Category A medical problem no longer will be excluded automatically from service. Rather, a person diagnosed with a Category A problem who still wishes to be considered for appointment will receive a full audiological examination. The new hearing standard allows the medical certification of more people suffering from hearing loss than would have been certified under the 1997 standard. Nonetheless, Carleton wouldn't pass either standard without the use of hearing aids.

The Massachusetts antidiscrimination law makes it unlawful, with certain exceptions, for any employer to refuse to hire, “because of his handicap, any person alleging to be a qualified handicapped person, capable of performing the essential functions of the position involved with reasonable accommodation.” Whether an accommodation is reasonable depends on whether it would “impose an undue hardship on the conduct of the employer's business.” The law permits employers to adopt “physical or mental job qualification requirement[s] with respect to hiring” so long as they are “functionally related to the specific job [and] consistent with the safe and lawful performance of the job.”