What is Attorney?

Legal Definition
1) Someone authorized to practice law; a lawyer. Also called attorney-at-law and public attorney.

2) Less commonly, an agent authorized to act on behalf of another person, but not necessarily authorized to practice law, e.g. a person authorized to act by a power of attorney. Also called attorney-in-fact and private attorney.
Illustrative caselaw
See, e.g. Savings Bank v. Ward, 100 U.S. 195 (1879).
See also
Legal Definition
One who acts for another byvirtue of an appointment by the latter. Attorneys are of various kinds.

2. Attorney in fact. A person to whom the authority of another, who is called the constituent, is by him lawfully delegated. This term is employed to designate persons who act under a special agency, or a special letter of attorney, so that they are appointed in factum, for the deed, or special act to be performed; but in a more extended sense it includes all other agents employed in any business, or to do any act or acts in pais for another. Bac. Ab. Attorney; Story, Ag. 25.

3. All persons who are capable of acting for themselves, and even those who are disqualified from acting in their own capacity, if they have sufficient understanding, as infants of a proper age and femes coverts, may act as attorneys of others. Co. Litt. 52, a; 1 Esp. Cas. 142; 2 Esp. Cas. 511 2 Stark. Cas. N. P. 204.

4. The form of his appointment is by letter of attorney. (q. v.)

5. The object of his appointment is the transaction of some business of the constituent by the attorney.

6. The attorney is bound to act with due diligence after having accepted the employment, and in the end, to 'render an account to his principal of the acts which be has performed for him. Vide Agency; Agent; Authority; and Principal.

7. Attorney at law. An officer in a court of justice, who is employed by a party in a cause to manage the same for him. Appearance by an attorney has been allowed in England, from the time of the earliest records of the courts of that country. They are mentioned in Glanville, Bracton, Fleta, and Britton; and a case turning upon the party's right to appear by attorney, is reported, B. 17 Edw. III., p. 8, case 23. In France such appearances were first allowed by letters patent of Philip le Bel, A. D. 1290. 1 Fournel, Hist. des Avocats, 42; 43, 92, 93 2 Loisel Coutumes, 14, 15. It results from the nature of their functions, and of their duties, as well to the court as to the client, that no one can, even by consent, be the attorney of both the litigating parties, in the same controversy. Farresly, 47.

8. In some courts, as in the supreme court of the United States, advocates are divided into counsellors at law, (q. v.) and attorneys. The business of attorneys is to carry on the practical and formal parts of the suit. 1 Kent, Com. 307. See as to their powers, 2 Supp. to Ves. Jr. 241, 254; 3 Chit. Bl. 23, 338; Bac. Ab. h. t.; 3 Penna. R. 74; 3 Wils. 374; 16 S. & R. 368; 14 S. & R. 307; 7 Cranch, 452; 1 Penna. R. 264. In general, the agreement of an attorney at law, within the scope of his employment, binds his client; 1 Salk. 86 as to amend the record, 1 Binn. 75; to refer a cause 1 Dall. Rep. 164; 6 Binn. 101; 7 Cranch, 436; 3 Taunt. 486; not to sue out a writ of error; 1 H. Bl. 21, 23 2 Saund. 71, a, b; 1 Term Rep. 388 to strike off a non pros; 1 Bin. 469-70 to waive a judgment by default; 1 Arcb. Pr. 26; and this is but just and reasonable. 2 Bin. 161. But the act must be within the scope of their authority. They cannot, for example, without special authority, purchase lands for the client at sheriff's sale. 2 S. & R. 21 11 Johns. 464.

9. The name of attorney is given to those officers who practice in courts of common law; solicitors, in courts. of equity and proctors, in courts of admiralty, and in the English ecclesiastical courts.

10. The principal duties of an attorney are, 1. To be true to the court and to his client; 2. To manage the business of his client with care, skill and integrity. 4 Burr. 2061 1 B. & A. 202; 2 Wils. 325; 1 Bing. R. 347; 3. To keep his client informed as to the state of his business; 4. To keep his secrets confided to him as such. See Client Confidential Communication.

11. For a violation of his duties, an action will in general lie; 2 Greenl. Ev. 145, 146; and, in some cases, he may be punished by an attachment. His rights are, to be justly compensated for his services. Vide 1 Keen's R. 668; Client; Counsellor at law.

12. Attorney-general of the United States, is an officer appointed by the president. He should be learned in the law, and be sworn or affirmed to a faithful execution of his office.

13. His duties are to prosecute and conduct all suits in the supreme court, in which the United States shall be concerned; and give his advice upon questions of law, when required by the president, or when requested by the heads of any of the departments, touching matters that may Concern their departments. Act of 24th Sept. 1789.

14. His salary is three thousand five hundred dollars per annum, and he is allowed one clerk, whose compensation shall not exceed one thousand dollars per annum. Act 20th Feb. 1819, 3 Story's Laws, 1720, and Act 20th April, 1818, s. 6, 3 Story's Laws, 1693. By the act of May 9, 1830, 4 Sharsw. cont. of Story, L. U. S. 2208, 10, his salary is increased five hundred dollars per annum.
-- Bouviers Law Dictionary
Legal Definition
In the most general sense this term denotes an agent or substitute or one who is appointed and authorized to act in the place or stead of another. In re Ricker, 66 N. H. 207, 29 Atl. 559, 24 In H. A. 740; Eichelberger v. Sitford, 27 Md. 320. It is "an ancient English word, and signi-fieth one that is set in the turne, stead, or place of another; and of these some be private and some be publike, as attorneys at law." Co. Litt. 51b, 128a; Britt. 285b. One who is appointed by another to do something in his absence, and who has authority to act in the place and turn of him by whom he is delegated. When used with reference to the proceedings ol courts, or the transaction of business in the courts, the term always means "attorney at law," q. v. And see People v. May, 3 Mich. GO5 ; Kelly v. Herb, 147 Pa. 563, 23 Atl. 8S9; Clark v. Morse, 16 La. 576.
See also
-- Black's Law Dictionary
Legal Definition
One authorized by another to act for him.
-- Ballentine's Law Dictionary