What is Disability?

Legal Definition
Disability is an impairment that may be cognitive, developmental, intellectual, mental, physical, sensory, or some combination of these, and that substantially affects a person's life activities. A disability may be present from birth or occur during a person's lifetime.

Disabilities is an umbrella term, covering impairments, activity limitations, and participation restrictions. An impairment is a problem in body function or structure; an activity limitation is a difficulty encountered by an individual in executing a task or action; while a participation restriction is a problem experienced by an individual in involvement in life situations. Disability is thus not just a health problem. It is a complex phenomenon, reflecting the interaction between features of a person’s body and features of the society in which he or she lives.

Disability is a contested concept, with different meanings for different communities. It may be used to refer to physical or mental attributes that some institutions, particularly medicine, view as needing to be fixed (the medical model). It may refer to limitations imposed on people by the constraints of an ableist society (the social model). Or the term may serve to refer to the identity of people with disabilities.

The discussion over disability's definition arose out of disability activism in the U.S. and U.K. in the 1970s, which challenged how the medical concept of disability dominated perception and discourse about disabilities. Debates about proper terminology and their implied politics continue in disability communities and the academic field of disability studies. In some countries, the law requires that disabilities are documented by a healthcare provider in order to assess qualifications for disability benefits.
-- Wikipedia
Legal Definition
The want of legal capacity to do a thing.

2. Persons may be under disability, 1. To make contracts. 2. To bring actions.

3. - 1. Those who want understanding; as idiots, lunatics, drunkards, and infants or freedom to exercise their will, as married women, and persons in duress; or who, in consequence of their situation, are forbidden by the policy of the law to enter into contracts, as trustees, executors, administrators, or guardians, are under disabilities to make contracts. See Pa7-ties; Contracts.

4. - 2. The disabilities to sue are, 1. Alienage, when the alien is an enemy. Bac. Ab. Abatement, B 3; Id. Alien, E: Com. Dig. Abatement , K; Co. Litt. 129. 2. Coverture; unless as co-plaintiff with her husband, a married woman cannot sue. 3. Infancy; unless he appears by guardian or prochein ami. Co. Litt. 135, b; 2 Saund. 117, f, n. 1 Bac. Ab. Infancy, K 2 Conn. 357; 7 John. 373; Gould, Pl. c. 5, §54. 4. That no such person as that named has any existence, is not, or never was, in rerum natura. Com. Dig. Abatement, E 16, 17; 1 Chit. Pl. 435; Gould on Pl. c. 5, §58; Lawes' Pl. 104; 19 John. 308. By the law of England there are other disabilities; these are, 1. Outlawry. 2. Attainder. 3. Praemunire. 4. Popish recusancy. 5. Monachism.

5. In the acts of limitation it is provided that persons lying under certain disabilities, such as being non compos, an infant, in prison, or under coverture, shall have the right to bring actions after the disability shall have been removed.

6. In the construction of this saving in the acts, it has been decided that two disabilities shall not be joined when they occur in different persons; as, if a right of entry accrue to a feme covert, and during the coverture she die, and the right descends to her infant son. But the rule is otherwise when there are several disabilities in the same person; as, if the right accrues to an infant, and before he has attained his full age, he becomes non compos mentis; in this case he may establish his right after the removal of the last disability. 2 Prest. Abs. of Tit. 341 Shep. To. 31; 3 Tho. Co. Litt. pl. 18, note L; 2 H. Bl. 584; 5 Whart. R. 377. Vide Incapacity.
-- Bouviers Law Dictionary
Legal Definition
The want of legal ability or capacity to exercise legal rights, either special or ordinary or to do certain acts with proper legal effect or to enjoy certain privileges or powers of free action. Berkin v. Marsh, 18 Mont 152, 44 Pac. 528, 56 Am. St Rep. 565.

At the present day, disability is generally used to indicate an incapacity for the full enjoyment of ordinary legal rights; thus married women, persons under age, insane persons, and felons convict are said to be under disability. Sometimes the term is used in a more limited sense, as when it signifies an impediment to marriage, or the restraints placed upon clergymen by reason of their spiritual avocations. Mozley & Whitley.

Classification. Disability is either general or special; the former when it incapacitates the person for the performance of all legal acts of a general class, or giving to them their ordinary legal effect; the latter when it debars him from one specific act. Disability is also either personal or absolute; the former where it attaches to the particular person, and arises out of his status, his previous act, or his natural or juridical incapacity; the latter where it originates with a particular person, but extends also to his descendants or successors. Lord de le War re's Case, 6 Coke, la; Avegno v. Schmidt, 113 U. S. 293, 5 Sup. Ct. 487, 28 L. Ed. 976.

Considered with special reference to the capacity to contract a marriage, disability is either canonical or civil; a disability of the former class makes the marriage voidable only, while the latter, in general, avoids it entirely. The term civil disability is also used as equivalent to legal disability, both these expressions meaning disabilities or disqualifications created by positive law, as distinguished from physical disabilities. Ingalls v. Campbell, 18 Or. 461, 24 Pac. 904; Harland v. Territory, 3 Wash. T. 131, 13 Pac. 453; Meeks v. Vassault, 16 Fed. Cas. 1317; Wiesner v. Zaum, 39 Wis. 206; Bauman v. Grubbs, 26 Ind. 42l; Supreme Council v. Fairman, 62 How. Prae. (N. Y.) 390.

A physical disability is a disability or incapacity caused by physical defect or infirmity, or bodily imperfection, or mental weakness or alienation ; as distinguished from civil disability, which relates to the civil status or condition of the person, and is imposed by the law.
-- Black's Law Dictionary
Legal Definition
Legal incapacity. See 18 Mont. 152, 56 Am. St. Rep. 565, 44 Pac. 528.
-- Ballentine's Law Dictionary