Most people think about “long term disability” as defining a state of affairs where an individual cannot provide an income for him or herself; that is, he or she cannot work. Indeed, in most instances disability does mean an individual is unable to work although in the context of ERISA disability claims there are policies which pay benefits when an individual cannot perform his or her “own occupation” and others which pay benefits for “partial disability.” However, it is best to over-simplify the issue and concede that, for the most part, to be found disabled under a policy of insurance an individual must not be able to work. The question then arises: what is it that makes an individual unable to work? There are lots of things that might prevent a person from not working: physical problems, mental problems, side-effects from taking potent medications for a medical condition, and so on.
But just what is it about such things that affect a person's ability to do work? Does a person have to be in a permanent comatose state to be entitled to receive benefits under a disability insurance policy? The answer to that question is usually a resounding “no,” though it is advisable to keep in mind that there are a few, bizarre and practically worthless “catastrophic” disability policies out there that come close to saying this. In any case, keeping to our intentionally primitive concept of disability, a person is disabled if they are unable to do work on a regular, sustained basis. In other words, if a person is not reliable because of his or her physical or mental problems then he or she is considered to be disabled. If a person was asked what physical problems might cause someone to be an unreliable employee, a ready answer would be that pain, physical restrictions/limitations and fatigue interfere with job performance. Similarly, if invited to articulate what types of mental issues constrain a person's ability to sustain employment, an appropriate response would be that problems with concentration, persistence, anger and so on affect reliability.
Accordingly, it is important to know why physical problems (e.g., pain, restrictions/limitations, fatigue) and mental problems (e.g., concentration, persistence, anger, etc.) constrain a person's ability to be reliable, i.e., to do work on a regular, sustained basis. Ultimately, the question as to whether a person with medical issues can be a reliable employee depends fundamentally upon three things: (1) the severity or intensity of the medical condition; (2) the frequency with which the issue arises; and (3) the predictability of the problem. As you might expect, the more severe or intense the condition, the greater the frequency of the issue, and the more unpredictable the problem, then the more likely theindividual is eligible for disability.