What is Attorney's Lien?

Legal Definition
The right of a lawyer to hold a client's property until the client pays for legal services provided. The property may include business files, official documents, and money awarded by a court. The right to an attorney's lien may come from the common law or from specific state statutes.
Illustrative caselaw
See, e.g. Gargano v. Liberty Intern. Underwriters, Inc., 572 F.3d 45 (1st Cir. 2009).
See also
Legal Definition
The right of an attorney at law to hold or retain in his possession the money or property of a client until his proper charges have been adjusted and paid. It requires no equitable proceeding for its establishment. Sweeley v. Sieman, 123 Iowa, 183, 98 N. W. 571. Also a lien on funds in court payable to the client, or on a judgment or decree or award in his favor, recovered through the exertions of the attorney, and for the enforcement of which he must invoke the equitable aid of the court. Fowler v. Lewis, 36 W. Va. 112, 14 S. B. 447; Jennings v. Bacon, 84 Iowa, 403, 51 N. W. 15; Ackerman v. Acketman, 14 Abb. Prae. (N. Y.) 229; Mosley v. Norman, 74 Ala. 422; Wright v. Wright, 70 N. Y. 98
-- Black's Law Dictionary
Legal Definition
The right of an attorney to retain his client’s property as security for the payment of his fees. See 3 Am. St. Rep. 567.
-- Ballentine's Law Dictionary